Tillandsia ionantha x 200
Heine, U. (1979) The Preparation and Observation of Tillandsia Trichomes Using the Scanning Electron Microscope, JBS Vol. XXIX(2)
A very warm welcome to our new members Rod and Kim Allen, Norm Johnston, Mandy Tilley, Ann and Noel Kennon, Gary and Colleen Claydon and Jennifer Nabbe who have all joined our group since the last issue of Newslink went out in early April. We wish you a long and happy association with our Society.
MONTHLY RAFFLE PRIZE ROSTER:
|Christine O/June Smith/Glenise Weston/Brian Baldwin/Phillip Robinson|
|Peter Netting/Sandra Southwell/Ailsa McD/Pat McIntyre/Tom Cross|
|Carmel G/Jenny McKenzie/Sharyn/Dawn Climent/Muriel Baldwin|
A reminder that our next workshop will be held on July 19—a Saturday, to accommodate members who are unable to come during the week. This time it will deal with the preparation of plants for Show and it is hoped that by ‘taking the scare out of’ what might be required for entering a plant into competition, we can entice newer members to enter into the Novice Section at our September Show. The venue: Sharyn Baraldi’s home at 25 Antrim Avenue, Warilla (Phone: 4296 2166) from 10.00 am until 2.00 pm and anyone interested is invited to attend. Bring your lunch, tea and coffee will be supplied.
QUEEN’S BIRTHDAY HONOURS LIST - DOREEN DUNWOODIE OAM:
|.||It is with a special measure of pride that we report that Doreen, who died quite suddenly last August, was mentioned in the Queen’s Birthday Honours List at the beginning of June. She has been awarded a posthumous Order of Australia Medal “For service to the community of the South Coast, particularly through Lifeline.” As mentioned in our October 2007 Newslink, Doreen had been a foundation member of Lifeline, giving 37 years of service, both as a counsellor and for 21 years had the unenviable task of setting up the 24-hour roster for telephone operators. However, we have now found out that she still found time for fulfilling the position of Secretary for the Gwynneville Girl Guides in the area for 15 years and held a similar position with the Keiraville Scouts Group for 10 years. Doreen also helped out with our Society, being one of the welcoming faces at the front desk for quite a number of years. Certainly the quiet giver!|
|- Janine Varley - Janine took out both the Morris Henry Hobbs Award as Division VIII (Artistic Arrangements) overall winner for her beautiful arrangement of bromeliads, entitled “Our Stash”|
|and a purple Award of Merit ribbon for a Miniature Arrangement entitled “Somewhere Out There” in which she had used dozens of Aechmea gamosepala flowers, individually wired and used to form a sphere - Stunning!|
|- Nina Rehak - Nina took out the “Best Judges’ Exhibit Award” for her beautiful Cryptanthus ‘San Juan’|
MEMBERSHIP FEES: A reminder that fees were due and payable by June 30th.
SPRING SHOW - PHOENIX PARK COMMUNITY CENTRE
Rob Roy Road, MALVERN EAST, Melway Ref. Map 69, D2October 4 - 5, 2008
Please take your Club Membership Card as interstate visitors will receive free admission, a warm coffee, free eats and a huge welcome — also a 10% discount on plants at Collectors’ Corner.
Graham and Carol Allen - Phone: 0412820859
Is planning a coach trip to visit the Melbourne Show
March 30th – April 4, 2009
Also visiting: Milawa Cheese Factory, Shepparton SPC/Ardmona Factory, Mornington Peninsula/Collectors Corner, Beechworth/Yackandandah, Cranbourne Botanic Garden, Mt Eliza prize-winning Nursery, Wodonga Nursery.
Cost around $800 pp Twin Share
(3-1/2 star motel accommodation, cooked breakfasts, 3 course dinners, some lunches, morning and afternoon teas and entry fees)
Contact Kaye or Lyal Thomas: 4284 9375
SYDNEY SHOWGROUND, SYDNEY OLYMPIC PARK
ADULTS $17/SENIORS-PENSIONERS $15
DISCOUNT TICKETS – GROUPS OF 10 OR MORE*
*Even though the tickets are purchased as a group, you don’t have to all go together—you can go different days!
*BROMELIADS* BSA, BS NSW, The Olive Branch, and others.
Hosted by The Bromeliad Society of South Australia
2009 Easter Weekend - Friday 10th – Monday 13th April
Early Bird - $185 from 1/8/08 to 31/12/2008
- $200 from 1/1/2009 and at the door
Adelaide Meridien is providing a limited number of rooms at reduced rates of Standard twin or double $125/night per room.
When booking provide Password “Bromadelaide2009”
Phone: 1800 888 228 or email firstname.lastname@example.org
See Eileen for further details and Registration Forms
Web site Link: www.bromeliad.org.au/BROMADELAIDE2009.htm
|SOUTH AMERICAN CACTUS EXPEDITIONS – (GUILLERMO RIVERA)|
NORTHWESTERN ARGENTINA (CACTUS AND BROMELIADS)
16 days - $2350, all inclusive except air fare – Cordoba November 15–30, 2008
CENTRAL BRAZIL (CACTUS AND BROMELIADS)
June 2009 – 18 days - $2950, all inclusive except air fare
PERU (CACTUS, BROMELIADS AND ALSO VISITING MACHU PICHU)
Prices in US dollars.
|ABC GARDENING EXPO Homebush|
|CENTRAL COAST BROM.SOC. SPRING SHOW Flora Festival Kariong|
|ILLAWARRA BROM.SOC. SPRING SHOW Uniting Church Russell St Corrimal 9-4|
|BROMELIAD SOCIETY OF VICTORIA – SPRING SHOW - See details this Newsletter|
|LEURA GARDENS FESTIVAL - www.leuragardensfestival.com.au|
|BROM.SOC.AUSTRALIA, SPRING SHOW, Burwood RSL|
|HILLS DISTRICT ORCHIDS OPEN DAY. 183 Windsor Rd Northmead, Email: email@example.com or (02) 9674-4720|
|HUNTER VALLEY GARDENS TOUR See below for details.|
|BROM.SOC.NSW SPRING SHOW 9-11 Wellbank St Concord|
|HILLS DISTRICT ORCHID OPEN DAY. 183 Windsor Rd Northmead, Email: firstname.lastname@example.org or (02) 9674-4720|
|BROMADELAIDE2009 Brom. Conference.|
|BROM.SOC.AUSTRALIA AUTUMN SHOW Burwood RSL|
|BROM.SOC.AUSTRALIA SPRING SHOW Burwood RSL|
|Neville Wood||Vriesea elata|
|Neville Wood||Vriesea hieroglyphica x platynema|
|Neville Wood||Billbergia ‘Curly Top’|
|Neville Wood||Neoregelia [Fosperior] ‘Perfection’|
|Coral Baldwin||Neoregelia ‘Fireball’ x ‘Morris Henry Hobbs’|
|Noel Pearce||Neoregelia ‘Shelldance’|
|Coral Baldwin||Neoregelia ‘Maya’|
|Coral Baldwin||Neoregelia ‘Lambert’s Pride’|
|Graham Bevan||Tillandsia brachycaulos|
|Catherine Wainwright||Tillandsia caerulea|
|Nina Rehak||Tillandsia crocata|
PLANT RESULTS - May 3rd, 2008
|Graham Bevan||Racinaea pugiformis|
|Neville Wood||Billbergia ‘Hallelujah’|
|Neville Wood||Guzmania sanguinea|
|Neville Wood||Aechmea recurvata var. benrathii|
|Rena Wainwright||Neoregelia [Fosperior] ‘Perfection’|
|Rena Wainwright||xNeophytum ‘Ralph Davis’|
|Norm Johnston||Guzmania ‘Magnifica’|
|Jenny Taylor||Cryptanthus ‘Scottish Mist’|
|Norm Johnston||Aechmea gamosepala (Giant form!)|
|Suzanne Burrows||Tillandsia cyanea|
|Phillip Robinson||Tillandsia lindenii ‘Pink Plume’|
|Dick Jamieson||Tillandsia flabellata|
PLANT RESULTS - June 7th, 2008
|Dick Jamieson||Aechmea weilbachii forma pendula|
|Neville Wood||Aechmea ‘Mirlo’|
|Nina and Jarka Rehak||Aechmea ‘Del Mar’|
|Carissa Morgan||Vriesea platynema var. variegata|
|Rhonda Patterson||Neoregelia ‘Predator’|
|Carissa Morgan||Neoregelia ‘Sunset’|
|Steve Morgan||Tillandsia atroviridipetala|
|Graham Bevan||Tillandsia brachycaulos x streptophylla|
|Steve Morgan||Tillandsia floribunda|
- August 2, 2008: Annual General Meeting
- - - - Topic: Using Bromeliads in Artistic Arrangements
- September 6, 2008: Topic: Experiments with Fertilisers and a Soil Additive - Neville Wood
- October 4, 2008: Topic: Vrieseas - Dick Jamieson
SOME NOTES ON PLANTS BROUGHT TO OUR APRIL/MAY/JUNE 2008 MEETINGS:
While the names may have been familiar, we had a couple of quite different-looking plants brought to our recent meetings, among them Norm Johnston’s beautiful Aechmea gamosepala, Bruce and Janice’s A. gamosepala with two inflorescences from the same rosette and Dick’s A. weilbachii forma pendula. Also, true to form, but varying from the more usual pendent inflorescence, was Neville’s Billbergia macrocalyx.
Aechmea ‘Del Mar’: Nina’s plant was certainly a stunner with its glorious cobalt blue, white and hot pink inflorescence. An A. fendleri cross with A. dichlamydea var. trinitensis was made by Patricia Bullis of Bullis Nursery in Princeton, Florida in 1996 (‘Del Mar’ has been referred to as the dwarf ‘Blue Tango’, maturing at around 2 feet) and was brought to Australia by Olive Trevor.
The US Patent Office describes it thus: “The new Aechmea is a product of a planned breeding program conducted by the inventor in Princeton, Fla. The objective of the breeding program is to create new Aechmea cultivars with compact plant habit appropriate for container production, desirable inflorescence colouration and good postproduction longevity.” This was certainly accomplished with this beautiful plant!—Ed.
Aechmea gamosepala: Norm Johnston brought a beautiful Aechmea to our May meeting, labelled A. apocalyptica, but thought to be a rather giant form of A. gamosepala. It had a tall, thick stem and the inflorescence was around 7-8 inches long, the sepals and flowers forming a closely knit head in a rich purple-blue. Other members commented that their A. gamosepala had sometimes performed this way!
Aechmea weilbachii forma pendula: Dick Jamieson’s beautiful plant, brought to our June meeting, also took a different form to the usual, having five inflorescences coming from the centre of the one plant. In addition to this, one of the stems was branched—partway along its length--into five separate pendulous inflorescences. Although the inflorescences were perhaps only about half the length of the usual form, it was a most beautiful and interesting plant to see. Dick told us that his plant had flowered normally the year before last, but last year there had been no flowering and so it was a great surprise to see what it had given him this year!
(Picture reprinted from BROMELETTER, Journal of The Bromeliad Society of Australia Inc., July/August 2008 issue, Vol. 46(4).)
Billbergia macrocalyx: This is a clustering species with only a few stiff, green leaves which form a tall, tubular rosette, growing to around 70 cm high. The leaves are splashed with cream and dusted with silver bands. The inflorescence is upright—rather than the more usual [for billbergias] pendent—and has showy, deepish pink bracts and large, soft green flowers, surprisingly edged in blue. They are frost hardy but need bright light to colour up, although direct sun should be avoided. They are indigenous to the tropical states of Minas Gerais and Bahia, eastern Brazil.
Guzmania ‘Magnifica’: This lovely plant was brought to our May meeting by our new member, Norm Johnston. This is a reasonably old cross, made by Richter in 1937, using two varieties of G. lingulata — var. cardinalis and var. minor. Sometimes known as ‘Scarlet Star’ the slender, soft green leaves of a small well-formed rosette show the influence of var. minor while the large star-like inflorescence resembles that of the variety cardinalis.
Racinaea pugiformis: Graham brought this interesting-looking little plant to our May meeting. It is quite chunky in appearance, with about a dozen or so silver-green leaves, and Graham’s plant, after 8 years, has rewarded him with around 10 inflorescences, which remind one of grass seed heads. I can find very little information on this species apart from the fact that it was originally listed as Tillandsia pugiformis and one site listed it as being collected in 1923 from Azuay State in Ecuador, between Ońa and Cuenca at an altitude of 2700-3300 m.
Tillandsia atroviridipetala: Steve’s beautiful little plant came in for a lot of oohs and aahs when it was presented at our June meeting. Named for its green petals (atro = black; dark; viridis = green; petalus = petals) this is a pretty, small, silver plant that likes quite dry, sunny positions. It comes from around nearly the geographic centre of Mexico, from Cuernavaca and Tehuacan, both cities around 50 miles south/south east of Mexico City--and at an elevation of around 2400 m-- where it prefers to grow, usually in a hanging position, on Commiphora (Burseraceae) trees which are characteristic trees of the pedrigalles (*lava flows). Rauh’s notes stipulate: “When mounting these plants in cultivation, the hanging position should be observed,” which confirmed Steve’s information that he grows his upside down, for if grown upright, water can sit in the rosette and the plant will rot and die! While many of our members indicated that they would love to have it, it is apparently very difficult to come by.
(Rauh, W. (1979) In: Bromeliads For Home, Garden and Greenhouse. Peter Temple, Ed. Blandford Press, Dorset, p. 92)
Vriesea zamorensis: Coral’s was another very striking and beautiful plant brought to our June meeting. Bright yellow flowers protrude from the reddish/orange/yellow multiple bracts, and the inflorescence will last for several months. Long, slender leaves are a shiny, light green, the plant growing to 30 cm in diameter and 45 cm high. It does not pup in the usual way, but more like V. elata, with the pups forming in the centre of the plant. Coral made this great find at Dapto Markets!
BASKETS FOR BROMELIADS
At our March meeting Dick Jamieson gave a demonstration on how he makes up hanging baskets for his bromeliads.
The idea is to provide a liner which will last for at least four or five years in good condition, so that mix is not washed over the top of the basket (as the more usual coir-type fillers allow to happen after a while as they shrink) or lost out of the bottom (as a more ‘fragile’ liner might allow to happen as it deteriorates over time!).
To form the liner:
1. Cut a square of shadecloth large enough to come up the sides of the basket, with a couple of inches to spare for folding over the top and into the basket.
2. Pull the cloth up over the outside of the basket, and, using bulldog clips, secure it to the basket rim, with the excess at the top folded over into the basket.
3. Form pleats to take up the extra cloth around the outside of the basket, and rub firmly along the creases with your fingers to take up the slack and to hold the shape.
4. Remove the bulldog clips and transfer the shaped shade cloth to the inside of the basket.
5. Into this now-lined basket, you may insert a second liner—e.g., coir/paperbark, etc.
6. Half-fill the basket with your preferred potting mix, leaving about two inches from the top free of soil.
7. Fold the extra two-or-so-inches of shadecloth liner between the outside liner and the inside insert.
8. Secure the liner to the top wire of the basket by wrapping a finer gauge wire around every inch or so.
As the inside liner will have a much shorter life than your shadecloth outer liner, when it comes time to repot your bromeliad, simply take out the inner liner and either clean it up or replace it, while the outer shadecloth liner should give you more good years of service.
Sometimes, if a basket has widely spaced bars, it may need to be reinforced, and this Dick does by using wire, fine enough to allow it to be twisted around each ‘rung’ as he works his way around the basket. Sometimes two of these rows might be necessary, say a couple of inches apart, although not every basket would need this extra re-enforcing.
Dick had quite an assortment of different baskets which he brought to our meeting to show us just how attractive bromeliads can look when planted up this way.
If, by any chance, you have any spare/unwanted shadecloth that might be looking for a home
then Dick would be very grateful to have it to use in making up his baskets.
Bringing it to our meeting(s) for pickup would probably be an easy way to go!
PRODUCTS THAT HAVE COME TO OUR NOTICE!
: - : PLANT PROTECTOR: At our June meeting Dick Jamieson gave a talk on a product that protects plants over a range of conditions, from the very cold in winter to the very hot in summer and gave this report:
“The product is “Carboxylated Hydrophilic Polymer” (a unique based polymer that reduces transpiration by plants and is rainfast when dry) which has been used by the nursery trade for years, although I came in contact with it more recently through connections with the orchid fraternity. On speaking with a number of orchid collectors, they had only glowing reports of its protective qualities and many more were also using it on their gardens in order not to experience disappointments on seeing their plants damaged in extreme conditions.
Some of the claims and applications the manufacturer makes are as follows:
1. Reduces moisture loss by up to 50%.
2. Eliminates sun and wind burn damage.
3. Increases frost tolerance by 4%.
4. Plant growth not impeded.
5. Applied by fine spray in dry conditions.
6. Allow to set 2-3 hours before watering.
7. The price to members for a 1 litre container is $25
(Dilution rate: 50ml/1 L water and Dick will have the product available at our monthly meetings.—Ed)
I am presently using the product for the first time this winter as I don’t want to experience the financial losses from plants I had after last winter’s frosts, and with the prediction of a very hot summer ahead I want to be ready with as much protection as possible.
If the product only saves just three plants it has paid for itself, although I am looking for much greater results, making the deal a good investment.”
: - : EL 64 (Aquaoil Enviroloc-64) - A SEALANT FOR TREATED PINE: This product has been brought to my attention as a reputedly safe way to seal CCA treated timber (treated pine) which many people might choose to use to build their shadehouses. For those unfamiliar with the very severe problems associated with the toxic effects on bromeliads when using treated pine, I would like to refer you to Neville’s excellent article which appeared in the October 2007 issue of Newslink.
EL 64 is an exterior weatherproof penetrating finish that effectively seals in the treatment chemicals in CCA and other pressure treated timbers preventing contact contamination and undesirable leaching into the environment. EL 64 has been tested to the OECD guidelines for the testing of chemicals standard en335 part 1. It can be used as an undercoat for acrylic coatings or, as it comes in a range of colours, can be used as a decorative/protective coating on its own.
I understand that it is produced by Quantum Timber Finishes in Victoria and is available through certain stockists in New South Wales including Bristol Paints in Nowra and Pambula, The Paint Place in Bomaderry and Paint Wholesalers in Kirrawee, Caringbah and Sutherland (although it may have to be ordered in).
: - : SEASOL: Neville has very kindly provided me with an article telling how he has come to rely on SEASOL to help his bromeliads survive and recover after traumas such as being pelted by hailstones the size of golf balls, that horrible New Year’s Day heat wave, severe, chilling winds and the coldest winter he had experienced in 60 years. A drenching with SEASOL®, using the spray pack that just clips onto the hose, helped them to recover in every instance and as we’re in the middle of some quite chill weather at the moment I wanted to let you know that this is perhaps something that you, too, can rely on to help your plants through the winter months. The full article will appear in a later Newslink!
TILLANDSIAS CLOSE UP!
by Laurie Dorfer, Illawarra Bromeliad Society
Tillandsias are one group of plants which have intrigued my interest for many years, but what has truly amazed me about this genus is how some of these plants grow in the most adverse climates yet still function as living plants, and not just survive but thrive.
The conditions under which most xeric species grow are generally hot through the day and cold at night, with very low rainfall and high solar radiation--where little other vegetation survives.
They generally only live on the humidity of the atmosphere for much of their lives and are therefore referred to as ‘atmospherics’ or ‘air plants’.
They grow predominantly as epiphytes and are therefore unable to obtain water from the soil: their roots are modified, with limited absorptive capacities, and are generally only used for anchorage. They are not parasitic and therefore do not gain access to food and water from a host.
So how then have these plants adapted to such harsh conditions? — In short, by morphological adaptations!
It is these mechanisms which are the focus of this paper, and which allow tillandsias to survive such adverse weather conditions. The most vital to their survival and those which largely affect cultivation techniques will be identified and their physiology discussed.
My objective is not to bamboozle people with fancy words, but to enable fellow tillandsia growers to understand some of these complexities, and, most importantly, provide some basic understanding to their growing requirements which is generally directly related to these mechanisms.
These mechanisms include, most importantly, trichomes and to a lesser extent water storage and CAM photosynthesis. Collectively, these are the most important morphological mechanisms by which atmospherics handle the conditions in which they grow.
Trichomes (pronounced try-combs)
Looking close up you generally notice the grey fuzzy leaf covering among the xeric tillandsias and these are the trichomes. They give the plants their general appearance, both in colour and in texture. Most are so small that they cannot be seen with the naked eye; however, there are some species quite advanced in their development, e.g., Tillandsia tectorum and T. crocata, which are relatively large and dense, making them easily visible to the naked eye. You may be thinking, if we cannot see them, then how can we use trichomes as an indicator on how to care for these plants! Individually this may be the case, but it is collectively that enables these practical observations to be made as it is generally the trichome shape and density which varies according to the habitat in which they grow.
Tillandsias which originate from more mesic conditions, e.g., T. imperialis, have smaller and less dense trichomes which you certainly can’t see with the naked eye: however, they are still present and provide the same functions. They don’t play such a significant role in water and nutrient absorption as for xeric species, because sufficient water and nutrients are collected within the tank and/or leaf bases. Also, the trichomes are not required to reflect excess solar radiation, because they generally grow in lower light levels.
Trichomes are present in practically all known genera of bromeliads, with the exception of the genus Navia (Leme & Marigo (1993) p. 22); however, they are most advanced and developed in the tillandsia genera, particularly those which originate from xeric conditions.
Trichomes are actually epidermal appendages and are sometimes referred to as hairs (due to their general appearance to the naked eye) or peltate scales (due to their shape when viewed under a microscope) - Figure 1.
They have several functions; however, the most important are water and nutrient absorption and protecting the plant against the sun’s radiant energy (PAR- Photosynthetic Active Radiation).
Due to their moisture and nutritional independence from a typical medium, trichomes have enabled these plants to colonize low rainfall and nutrient-poor epiphytic habitats. The areas in which these plants grow are generally referred to as dry or arid. But this depends on how you define dry. Yes, the areas are of low rainfall, but moisture is generally often present in the form of mist or fog; therefore it is not really dry if you have the ability to obtain it in this form. For example, in the Andean area of north-western Peru where T. tectorum survives, it receives no more than 10-50mm/year, but there is regular moisture available, though not in the form of rain but in the form of mist and fog. A dense sea fog, particularly in winter, spreads over the desert and into the valleys (Hromadnik 2005 p. 2) which provides the available moisture. This Peruvian coastal desert is referred to as a mist-desert, where the air contains a humidity of 90% or more and the area supports an abundant presence and diversity of tillandsia species. It is the highly developed trichomes that are able to capture this available moisture in the air making it available to the plant.
Trichomes are made up of not just living cells, but dead cells as well, which collectively assist in water absorption. Besides much variation in the appearance between species of tillandsia trichomes, there are some basic morphological similarities. As these are the highest developed subfamily in regards to trichomes, they have the most regular cell arrangement, being in a multiple of two (Rauh et al, 1973). The centre consists of a group of four concentric empty cells called the central disc cells. These are surrounded by a further series of concentric empty cells called ring cells, which are in numeric sequences of eight, sixteen and/or thirty two (Figure 2). The atmospherics generally bear trichomes which consist of two or three series of ring cells. These are then surrounded by the long, elongated wing cells, which then generally support 64 cells; however, these sometimes vary, reaching more than 100--e.g., T. hildae. Generally we can get a sequence of 4 + 8 + 16 + 32 + 64, but there are many variations where one or more of the cell rings can be omitted (Rauh et al, 1973), such as 4 + 8 + 32, or 4 + 8 + 64, or 4 + 8 + 16 + 64, or 4 + 8 + 16 + 32 + 64. This collective group of cells is called the shield, which is the most visible part and consists entirely of dead cells. These are connected to the leaf interior by the stalk cells, which are all comprised of living cells. It is the shield and stalk cells together which resemble an umbrella and has given them the term peltate scales (peltate - meaning umbrella-like and scales--the appearance of the shield). Also, it is these which you see when a leaf is scraped with a fingernail. The fluff we see is generally mostly wing cells and some stalk cells: they are very fragile appendages.
The trichome cells of the shield die once they mature, leaving empty cells. They are made up of cellulose, which is a very flexible material, and once dead, it is only these cellulose cell walls which remain. This enables them to quickly absorb and hold large quantities of water due to this flexible nature.
Unlike a drop of water which beads on a normal leaf surface, water spreads very rapidly across the leaf surface of a tillandsia. This is due to the shape and gaps between individual trichomes and capillary action: just like watching the movement of water through a kitchen paper towel. When water comes into contact with the shield, the water quickly spreads to form a thin, uniform film, and the empty cells then draw it in like a sponge. As the cells fill with water, the thick upper walls of the central disc cells and ring cells become turgid and swell (Figure 2), and rise within the concavity, allowing water to move freely into the living cells to the stalk; simultaneously the wing cells are drawn downwards towards the leaf epidermis. This is due to the relationship that the outermost ring cells have with the wing cells: by having the reverse configuration--i.e., thin flexible upper cell walls and thick, rigid lower cell walls, a torsion is created by their interaction, so that as the lower cells walls become turgid and straighten, the wing is drawn downwards (Isley 1987, p. 206).
The increased cell volume of the central disc and ring cells, together with the downward movement of the shield, produces a minute suction (Benzing 1977 ) which assists in maximising water absorption. From there water moves through to the dome cell and into the stalk cells by osmosis, where it then enters the leaf interior (mesophyll), to be used by the plant or stored.
When the surrounding moisture no longer exists, the leaf surface dries very quickly and regains its grey, fuzzy appearance as the wings are again flexed upwards. The central disc cells sit in a slight depression, which when dry and in a flaccid state, collapse and seal this concavity. This snug fit prevents the escape of moisture from the leaf interior via the stalk cells. In doing this it forms a one-way valve, allowing the plant to quickly absorb moisture yet minimise water loss during dry conditions. Without this closure, water would be continuously drawn out of the leaf interior by transpiration.
Xeric species need to dry out very quickly, as they can only maintain wet foliage for a short period of time. This is because as the trichome shields depress over the leaf epidermal when wet, they block the stomata (breathing holes) and act as a barrier to vital respiratory processes. For a period of time, possibly a day to two is generally not critical, but there is a point reached when the plant is starved of oxygen and they will suffocate just like us. This is most important during the night, which will be discussed later, and also in warmer climates or during the summer months, as more oxygen is consumed by the plant as the metabolic rate increases, thus increasing the demand for oxygen. This is the reason why you often hear that good air circulation is essential for xeric tillandsias. Stagnant air is a high contributor to the decline and death of tillandsias which may cause rot by suffocation (Isley 1987, p. 190). This is generally easy to detect, as the emerging growth sometimes shows yellowing leaf tips turning brown, and/or, most often, with a slight tug the emerging leaves come away from the apical meristem. Most often, by the time it is detected it is too far gone. Tolerance to suffocation varies among species and generally reflects their climatic origin.
T. argentina, T. atroviridipetala and T. xerographica are some which have low tolerance. If gaseous exchange is blocked for more than a couple of days, they generally do not handle it and the plant will generally be adversely affected. Due to a very dense trichome development of T. atroviridipetala, particularly at the leaf sheaths, and the shape and positioning of foliage, it is very sensitive to suffocation and water sitting in the cup: if grown upright, the meristem will often die if kept moist for more than a day or two. Therefore, these species need to grow or be positioned sideways or upside down.
In some species the trichome wings are held vertically to the leaf surface which gives them a fuzzy appearance and assists in the epidermal drying, e.g, T. tectorum which has large trichomes with asymmetrical shields and an extension to the wing; this is due to the climatic origin which supports regular mist/fog and therefore these mechanisms are required to assist in quick drying.
Generally, wings cells can be either symmetrical or asymmetrical with an extension (Figure 3). These vary considerably between species depending on the climatic origins that each comes from, and whether the moisture available is in the form of rain or fog/mist. It also depends on the position of the trichomes on the leaf blade. The trichomes from the middle of the leaf blade are generally centric (symmetrical), while the wings of the trichomes from the margins of the same leaf show an extremely eccentric (asymmetrical) shape--e.g., T. tectorum, T. usneoides (Rauh et al, 1973). These hairy-looking trichomes are sometimes referred to a ‘dewtongues’, as they are able to absorb even small traces of dew or humidity. If the shield edges turn up, then the leaf appearance will be rough--e.g., T. ionantha; if the shield is flat and symmetrical, it gives a smooth appearance--e.g., T. xerographica (Isley 1987, p. 208). If the wings cells are more developed on one side, it gives a grey, fuzzy appearance--e.g., T. tectorum, which increases the surface area exposed to the atmosphere for greater access to moisture, usually in the form of mist or fog. Therefore, we can now start to visualise the trichome physiology by the general appearance without having to see these under a microscope. This will become even clearer the more I explain. From this, we can assume their climatic origins and use this as a way of looking after our plants.
The wings of most species are flexible, which when wet depress over the leaf surface, and this is typical for the grey-leaved, fuzzy species, but this can vary with some species like T. bulbosa, T. butzii and T. cyanea which are more rigid and inflexible. This is in direct relation to their natural growing environment, being rather shady and subject to increased rainfall or humidity. Suffocation would result if the shields were flexible. Furthermore, the abaxial (upper leaf surface) trichomes of these species are transparent (Isley 1987, p.208), which allow greater light penetration rather than being reflective. This gives the plants a more green appearance as the chlorophyll can be observed. Therefore, the greener the plant (when dry), the more moisture and less light they require.
When dry, the dead cells of the shield are filled with air that reflects sunlight. This gives the xeric species a grey/silvery appearance. When wet, the air is replaced with water and therefore absorbs greater light, making the cells transparent and causing the green chlorophyll beneath to become more visible. This is why a colour change is noticed when watering.
Trichomes appear over most of the plant surface, including leaves, stem (caulescent forms) and inflorescences. Foliar trichomes cover the entire leaf surface, upper (abaxial) and lower (adaxial) surfaces of the leaf, but vary in density not only between species but also by the positioning on the leaf. They can appear in bands or stripes—e.g., T. hildae, with the greater density providing the grey/silver markings, or increase in density towards the leaf sheath. Generally, grey-leaved tillandsias have higher overall density and prefer higher light because they scatter or reflect a large percentage of that light, and green-leaved tillandsias have lower density and prefer lower light levels because they absorb greater light. The density provides an indication of the condition and the amount of water these plants prefer. The grey/silver tillandsias generally live in areas of little rainfall but with high light and humidity, the green leaved tillandsias with low trichome density generally live in areas of regular rainfall with reduced light levels (Rauh 1990, p. 54). This is where we can again start to see how knowing about these structures may assist you on where to place your next tillandsia. Also, most tillandsias have a higher trichome density in the leaf sheaths, which I assume is because this is where most water and nutrients may accumulate. Therefore, when foliar fertilising, always provide a good soaking within the leaf sheaths to maximise nutrient uptake.
Many xeric species with dense trichomes (grey/silver) grow in high light or are exposed to full sunlight and are therefore able to tolerate high solar radiation and reflect infrared radiation: this is in direct relationship to the dense trichomes reflecting light due to the air held within the dead shield cells. This protects the leaves from potential heat build-up, particularly species with trichome wings which are parallel to the leaf surface--e.g., T. xerographica--which can lower leaf temperatures, thus reducing water loss by transpiration. These are species with a generally smooth appearance to the leaf surface. The flattened wings also provide a void or separation between the leaf epidermis and wings which provides a kind of insulation and cools the leaf. T. fasciculata reflects between 42% and 47% of the visible light on the adaxial leaf surface (Benzing 1977(4)). Benzing had also carried out experiments where trichomes were removed from specific leaves on a plant and left on others of the same plant: he had detailed that the leaves of T. flexuosa where trichomes caps were retained were up to 23.8% cooler than those with the caps removed.
Besides water, tillandsias also require nutrients. Again, roots cannot provide the necessary nutrition for them to grow like most other plants and therefore have had to find other means of obtaining these essential elements--or could it be that other more efficient means were found and roots then diminished in function and were only required for anchorage? Whichever came first, it is the trichomes which are also nutrient-absorbing organs and enable these plants to obtain these essential elements. As nutrients can only be assimilated in the form of dissolved minerals, water is an essential part of the process and therefore they need to work correspondingly with water absorption. The only nutrients available to them is what lands on their leaves, as either dust blown in with the wind or fallen as dissolved in the rain (Crayne 2000). Water can also be enriched by additional nutrients leached from plant/organic tissue as it passes down the forest/cliff profile, but these are not great. With such little available, the plants have had to develop extremely good water and mineral efficiencies (Benzing, 1977 (3)). It is also thought that the trichomes may directly assist in nutrient absorption by their course texture as created by their wings which may intercept airborne particles.
Some texts mention that trichome morphology has the potential to form part of taxonomic identification. Criteria such as whether the trichome is radial or bilaterally symmetrical, measuring the area of the central cells versus the wing cells, number of wing cells per trichome, also the degree which the trichome is raised above the surrounding tissue (Heine 1979). This concept has never really been taken up, due largely to differences in trichome morphology within a species. Depending on where it is observed, trichomes may vary from the upper leaf surface and lower leaf surface, distally and proximally on a leaf surface, leaf blade and leaf base. The information required would become very complex which is likely to further complicate the issue: floristic identification remains much simpler without the variation.
The trichome function within the tillandsia genus has become extremely successful and efficient; however, such efficiency comes at a cost. A potential weakness is that they are extremely sensitive to air-borne pollutants and particular minerals/metals. In Latin America they are used as air pollution monitors: T. usneoides is used in Costa Rica to estimate the levels of potentially toxic metals such as cadmium, copper and lead, whereby they are taken from unpolluted areas and moved to polluted parts of city. They are later harvested and the concentration of these metals in their tissue analysed, which provides rather accurate estimates. Also, in the gold mining towns, T. usneoides is used to monitor mercury contamination, which is a by-product of their processes (Crayne 2000). Because of this sensitivity, they can be very susceptible to leachates from chemicals in paints, wood preservatives, metals, some insecticides, even excess salts in fertilizers. They can get salt toxicity, which is shown by brown edges to the leaves from some inorganic fertilisers. That is one reason why Phostrogen® fertilizer is often used as a water-soluble fertilizer; besides the presence of nitrate, it has very low salt residue in it as opposed to some other proprietary products. Observations have been made, although did not lead to their demise, by the emissions from a parked vehicle (carbon monoxide) idling alongside a collection of tillandsias; this varied between species, as mainly the fuzzy leaved species were affected. But, the actual death was observed as caused by sawdust from treated timber (CCA - Copper Chrome Arsenate) settling on the foliage as blown in from a neighbouring property undertaking construction works. In hindsight, this may have been minimised if the sawdust had not been washed off with water: rather it should have been brushed off, as absorption generally only occurs once in solution. Also, new galvanised fencing wire supporting a collection had caused damage to particular plants which were in direct contact and/or likely to have obtained leachate: no problems seem to occur with aged galvanised wire.
Part 2 – Water Storage and CAM Photosynthesis will appear in our October, 2008 issue.
As part of the
‘SPRING INTO CORRIMAL’ FESTIVAL
September 13 – 14, 2008
There are all types of jobs going over the 3 days--from setting up the display and competition and sales tables from 2.00 pm on the Friday to packing up on the Sunday afternoon. As we provide tea/coffee/cakes/slices to visitors (plus lunch for workers and judges) on the Saturday, providing goodies and/or some time in the kitchen could be one way of helping, manning the information and raffle tables another. We also need sales and display plants so if you have any extra bromeliads at home that might be suitable we hope that you will bring them along.
The workshop at Sharyn’s on Saturday, July 19 is aimed at ‘taking the scare out’ of perhaps entering plants into competition for the first time. Newer members have been bringing some very beautiful plants to our meetings and as I know that the public would love to see them too I’m hoping that you will give serious consideration to bringing some of them to our Show.
Steve’s cute article, printed below, lets you know just how ‘easy’ it can be to take out top honours!
A FAMILY AFFAIR
By Steve Morgan.
I have been prompted to put pen to paper by a number of recent events involving my family. I am a keen bromeliad collector and have a backyard full of them. Recently, I had planned to extend a shade shed past the bedroom window of my eldest son Mitch (17 years). The Honourable Minister for War (my wife Janelle, age withheld) soon put a stop to this plan, saying I would stop light and air entering the room. I explained that since Mitch would be leaving home when he finishes school, what’s the problem? A mere six months and he’s gone. This reply received a big serve of hot tongue followed by lashings of cold shoulder so I thought I had better put that plan on the backburners for now.
As you may have gathered by now, Spousie and the eldest son have no love of bromeliads. They often tell me they would be happy with green cement or at most AstroTurf.
This brings me to my other children: Lucas (14 years) and Carissa (12 years). These two sometimes come with me to Society meetings, Lucas does like the plants and Carissa goes because she gets Kentucky Fried Chicken on the way home!
The Brom Club Show was on in September ’07 and this meant the 3 keen??? members of the family must select their plants to enter in the show. This is done with a great deal of knowledge and skill. Lucas just walks through the shade sheds and picks what he likes the look of. Carissa makes it easier still, anything with the colour pink in it will do. Confident as a result of the previous year’s show, Dad takes hours of deliberation using all his skill and knowledge to pick the best plants.
Selections made and off to the Show. The results:
- Lucas: : : : Champion Plant of the Show
: : : : : : : Novice Champion
- Carissa : : : : :Two 2nd placings.
- Dad . . . . . . . . . . One 3rd place
I have been hearing about this result for the past six months – Oh Joy! Father’s Day being just after the show, I received a card from my eldest son, I quote:
Happy Father’s Day!
Dad, and just so you know, next time at the Bromeliad Show,
“Success is a lousy teacher, it seduces smart people into
thinking they can’t lose.” _ Bill Gates
Therefore, you already have the upper hand and you could
improve on that lousy 3rd place (I think that the Novice is your
speciality). _ Love Mitch
On the upside, I have been linked to Bill Gates, and I gain great strength from the support given to me by my family.
Sometimes it’s hard being addicted to Broms!
SIXTEENTH ANNUAL SHOW
September 13 – 14, 2008
|Aechmea||Individual specimen plant|
|Billbergia||Individual or multiple permitted|
|Neoregelia||Individual specimen plant|
|Neoregelia||Miniature (under 200mm) - Individual specimen plant|
|Tillandsia||Individual or multiple - May be potted or mounted|
|Vriesea/Guzmania||Individual specimen plant|
|Bromeliad not listed above||Individual or multiple permitted|
|Mounted Tillandsia||Minimum of three (3) established plants which may be the same or different|
|Mounted Bromeliad(s) other than Tillandsias||Established plants which may be the same or different|
|Established colony:Aechmea/Vriesea||Minimum of 3 plants|
|Stoloniferous Colony: Neoregelia||Minimum of 3 plants|
. SECTION 2 - NOVICE
|Aechmea||Individual specimen plant|
|Neoregelia||Individual specimen plant|
|Tillandsia||Individual or multiple permitted - May be potted or mounted|
|Vriesea/Guzmania||Individual specimen plant|
|Bromeliad not listed above||Individual or multiple permitted|
. SECTION 3 - CREATIVE
|Basket or Decorative Container||minimum of three (3) plants which may be the same or different – no embellishments.|
|Bromeliad Garden – Any Container||Embellishments may be used.|
|Artistic Arrangement||to consist of predominantly bromeliad material – Embellishments may be used.|
_ In classes covering “Individual Specimen Plants”, pups are permissible on the adult plant only if they are so small that their removal might jeopardize their survival.
_ When allowing for multiple plants the key word is “interconnected”—i.e., they must all originate from a single plant.