Articles: BULB CHAT June 2003 PDF Print E-mail
Thursday, 26 May 2011 23:36

BULB CHAT JUNE 2003 No. 36

EDITORIAL COLLABORATION

Due to unavoidable circumstances this months BULB CHAT is a collaboration by the Past and the Current Editors of BULB CHAT. I thank Mr AT de Villiers for his time and effort - The Ed.

IBSA BULB AND CORM SYMPOSIUM - AUGUST 2003

This would be your last chance to register for this exciting IBSA event. Closing date for final bookings has to be the end of June. We are giving final figures to Goudini Spa early in July.

If you have not booked yet do so immediately. Those members who owe the balance of their symposium fees should please send it to the Secretary, at the normal IBSA address.

We are looking forward to seeing and meeting all the delegates in August.

MARCH MONTHLY MEETING

We had previously reported about the March Monthly Meeting. The fantastic pots of spectacular Nerines that were on display had been discussed. The first Polyxenas to flower were seen as well. Represented were Polyxena longituba, Polyxena corymbosa and Polyxena ensifolia var maughanii. The last one we all knew as Polyxena maughanii up till last year. ( see IBSA bulletin 51 of October 2002 )

SEED DISTRIBUTION 2003

The allocation of seed by mail order has been an unpleasant experience this year. We tried to ensure more seed available by reserving one third of each species from those submitted for the AGM but we still experienced demands far in excess of availability. We would have 19 demands but only one packet available. Many members will be disappointed and we are very sorry about this. We have tried to even out the disappointments but it has been almost impossible to be fair. At the same time we have many species which were not demanded or only a few packets wanted. We were surprised at some of the small demands : Moraea loubseri, thought to have been extinct for nearly a third of a century, was under-demanded. Tritonia florentiae, that very beautiful and almost unknown species, was so under-demanded that we have 16 packets left on hand. Moraea lurida is another example - We have about 40 packets left over. Since M. lurida can be either black or golden it is worth sowing a lot of seed to ensure getting an example of each colour

OUR CHANGING WORLD

The world is warming. Many have tried to disprove this statement, but the best evidence points to a disconcernable human impact on global climate. There remains huge debate however on what this warming means for humans and the world we live in. It is plain to see that climate changes will have an impact on our plants. Our plantlife is sensitive to weather and climate, as is wonderfully clear every spring. Changes forecast for South Africa would include possibly wetter winters but also drier summers. A rise in the sea-level will change the coastal environment with subsequent flooding of certain areas rich in bulbs and corms. Other areas of South Africa could possibly become too dry for many of the bulbs and corms presently growing there.

Climate change is possibly the biggest challenge that mankind has ever faced. It poses direct threat to mankind and to the fragile ecological systems that support us and our bulbs and corms. Can we afford to ignore the threat?

THE TAXONOMIC REVOLUTION

We are living through a revolution. For 250 years we have been loyal to the Linnaean concept of cognate species grouped together into genera. A genus comprising those species which shared a common or several common characteristics based primarily on a set of morphological characteristics could be described and defined to distinguish it from any other genus. In comparatively recent years a genus could be drawn as a cladogram to demonstrate the mutations that must have occurred in the course of evolution to produce the separate species. It was a tidy, logical and understandable progression not interrupted by specimens of other genera. Now we are being subjected to a taxonomy based on DNA analysis, a science still in its infancy, which discards morphology as the determinant of relationship and substitutes genetic proximity. We in IBSA were first subjected to it by the revision of the genus Moraea which sunk the genus Galaxia into the middle of Moraea. None of us liked it but few of us realized the implications. Now if we were to draw a diagram of relationship we would have to extend a straight line or several straight lines along which species of different genera are interspersed. We would be creating a complex but, unlike a genus, the component species would have no common identifiable characteristics. Such a complex could not be defined. Genus was an inclusive concept, the component species all and only those which shared the determining characteristics. A DNA complex would include many components which had diverse characteristics and, moreover, would separate similar species by utterly different ones. When DNA taxonomy is applied to Lachenalia, Polyxena and who knows what else we will find various Lachenalia and Polyxena mixed helter skelter along the lines of relationship.

We need to remember one of the abiding features of a revolution. The generation which begins it is not the generation which refines and developes it. A younger generation takes over and introduces new and exciting applications. At present the Botanists who are leading the revolution are still imbued with the Linnaean concept and will try to apply generic names to non generic complexes. They will try to make definitions of disparate specimens. No doubt a new generation will devise a taxonomy to take care of it all but it is doubtful whether any of us will live to see it. Meanwhile we must stick to names that we can understand. To us a Galaxia is still a Galaxia.

GREEN LACHENALIAS

At the May monthly meeting we touched on Lachenalias with green flowers. The most well known green Lachenalia is obviously Lachenalia viridiflora. At the meeting there were some spectacular specimens on show.

Lachenalia viridiflora was discovered 50 years ago by Mr Harry Hall in August 1953 near Vredenburg on the Cape West coast. This species has a very localized distribution in the Vredenburg district. Lachenalia viridiflora is restricted to humus-rich, shallow depressions on the granite outcrops. The two lanceolate, bright yellow-green leaves may be plain or darkly spotted. The leaves are even occasionally pustulate. The inflorescence is racemose ( having pedicels ) and the flowers are cylindrical. The perianth segments are green or turquoise. The protruding inner segments have whitish tips and a viridian green central stripe.

Lachenalia viridiflora does extremely well in cultivation and is highly sought after, because it makes an attractive pot. It flowers early, May to July, when few other plants are flowering.

Lachenalia undulata is another Lachenalia with green flowers. This is another early flowering species. The flowers are green to greenish-brown. The outstanding feature of this Lachenalia is the undulate or crisped leaves. Lachenalia undulata flowers during May and June and they are common around Klawer and Vanrhynsdorp. They belong to a group of Lachenalias which includes Lach zebrina, Lach isopetala, Lach aurioliae and Lach obscura which tends to sulk in the pots. Very often no growth is seen in the pots and when you scratch around in the soil you find the bulb in perfect condition but not even attempting to make leaves. It would be helpful to know what triggers growth in them.

The other obviously green flowering Lachenalia is Lachenalia aloides var vanzyliae. These plants occur naturally in the Piketberg, Porterville and Cederberg mountain ranges. The one or two leaves could be unmarked, but are usually densely marked on the upper surface. The pendulous flowers are cylindrical ( Aloe like ). The outer segments of the flower are pale blue at the base shading to light green. The protruding inner segments are yellowish green. According to " The Lachenalia Handbook " this variety of Lachenalia aloides can become robust under cultivation and multiplies rapidly. In practice this is not the case, because very few IBSA members at present have specimens of Lachenalia aloides var vanzyliae growing. Flowering time is September and October.

This variety was named after Mrs. L van Zyl who first introduced the plant to Kirstenbosch in 1927. This same Mrs. Van Zyl also grew a Romulea in her garden which Miriam de Vos thought was a hybrid between Romulea subfistulosa and Romulea sabulosa.

AUTUMN EXCURSIONS

It is worth repeating that it is a waste of effort pre-planning IBSA excursions for the Autumn flowering of bulbous plants. They cannot be relied on to flower in the same place at the same time year after year. Their flowering period is generally very short. The only useful expedient is to mount a private expedition at very short notice when a report comes in. There just is not enough time to alert all the ( local ) membership. On the weekend of 5/6 April Rod & Rachel Saunders passed through Nieuwoudtville. They reported the start of what promised to be a magnificent flowering. We were able to cobble together a party of 5 for the weekend of 12/13 th. We saw acres upon acres of Brunsvigia bosmaniae such as you would not imagine. Two members of our party passed through the locality the following weekend ( Easter ). Not one flowering B. bosmaniae was to be seen. A preplanned excursion one week early or one week late would have been a complete fiasco.

THE SCENT OF EMPODIUM

We have all experienced that some specimens of Empodium are scented while others, of the same species, are not. Dee Snijman and John Manning have solved this problem. In most flowers the scent cells are in the surface of the tepals but not in Empodium. The scent is carried in an appendage on the tip of the anther and nowhere else. So long as the anthers remain whole and undisturbed the flower will smell but when the appendage is damaged or lost by the anther being broached the smell will be lost. If there are other plants with this peculiar mechanism we must confess that we do not know of them but perhaps we should begin looking more closely.

THE GENUS MASSONIA

Two different Massonia species were on show at the May monthly meeting. They were Massonia depressa and Massonia pustulata. These two Massonia species fall into different groups when it comes to identification. The one group has large anthers ( more than 2,5 mm long ) and the perianth tube has a wide mouth. Massonia depressa falls in this group. The other representative of this group is Massonia grandiflora, a rare species found in the Karoo.

The other group has small anthers ( up to 2 mm long ) and the perianth tube is narrow. Massonia pustulata as well as Massonia echinata and Massonia pygmaea are found in this group. The two leaves are always prostrate, but pustulate leaves do not always mean that you are looking at Massonia pustulata.

Massonias are winter-growing and undergo dormancy in summer. They look best when planted singly in pots and need protection from snails and mealy-bugs.

NIEUWOUDTVILLE : APRIL 12/13

The expedition to Nieuwoudtville had two aims : to view the B bosmaniae and to collect a specimen of the pollinator of a whole guild of currently flowering plants. Since our aim was simple and limited we drove up the N7 intending to photograph the B bosmaniae on the Saturday, stay the night at the Van Wyk's guesthouse and visit the Gifberg on the way home on the Sunday. We expected to find the pollinator most easily on the Gifberg. The first intimation we had that the excursion might be different was the sight of a clump of about 20 Brunsvigia orientalis in all the glory of their bright red flowers at km post 69. As we approached Klawer we passed smallish colonies of Brunsvigia bosmaniae and Haemanthus coccineus, particularly at km post 37,5. At the petrol station in Klawer there were Haemanthus crispus and H. coccineus. Since it was still early on the Saturday we drove past Vanrhynsdorp up the N7 as far as the Sishen-Saldanha rail bridge and checked the progress of Ixia acaulis and Babiana carmineus. We also saw Brunsvigia radula in flower. We then retraced our steps and made for Nieuwoudt-

ville only to be stopped at the major bend at the bottom of the Pass. There were masses of Hessea stellaris in strong pink bloom. At the top of the Pass there were several species in bloom, notably Strumaria watermeyeri, Brunsvigia minor and Bulbine aloides.

The weather was perfect and from a distance we could see the Klipkoppies of the Nieuwoudtville Nature Reserve rising out of a sea of pink. It was said that never before had there been such a display and we could well believe it. Not only on the Klipkoppies but on every farm around there were the same vast fields of massed B bosmaniae in a multiplicity of shading of pink and white together and even a few pure white blossoms. Growing among them were little white Strumaria tenella. We even saw and captured the pollinator that we sought so we had no need to go onto the Gifberg on the Sunday and could return directly to Cape Town after a late breakfast.

THE "TRIGGER" : A PERSONAL SPECULATION A.T.de Villiers

What follows is my personal speculation, based on observation neither sufficiently broadly based nor adequately researched. I believe it deserves proper botanical investigation to verify or disprove it. Furthermore it is restricted to bulbous plants although I think the principle may apply to corms but, if so, the mechanism would probably differ.

It is based on a belief that the bulbs, or most of them, break dormancy according to a time clock. A strong case could be made for it being related to summer temperature and length of hot weather. Personally I incline to a time clock basis. It is also based on a belief that it does not apply, or only sometimes applies, to bulbs in cultivation because a horticultural environment has different constraints. I believe that the bulb begins its preparations for emerging from the soil unaffected by the climatic and environmental factors current at the time, which is why I tend to the time clock hypothesis. I believe that the shoot developes to a height where it becomes influenced by the external factors. If those are inimicable I believe the development ceases but is not aborted but remains in stasis. This point would vary from species to species and to the strength of the external factors. I believe that this state continues until those factors offer the appropriate trigger. This trigger may be water ( rain, mist, surface wash, etc ). Dr Du Plessis advances the theory of atmospheric pressure but, of course, atmospheric pressure and the actual occurrence of rain are often interrelated. On receipt of the trigger the final shoot development takes place and it bursts through the soil surface.

I have watched this phenomenon in specimens of Gethyllis and I am strongly reminded that you may travel through Bushman Land seeing no vestige of bulbous activity ; then a storm breaks and within a day or two the veld is covered in emerging bulbous plants such as Lachenalia species. I am told that the same phenomenon is common in the southern United States as well as Central America. The same hypothesis makes a lot of sense of the fire trigger. There must, I presume, be a limit to the period in stasis before the bulb aborts but I think that it is more likely that abortion occurs if the external factors deteriorate to an extent that the shoot has risen too close to the soil surface, i.e. that the state of stasis is now too high.

 

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