Articles: BULB CHAT July 2002 PDF Print E-mail
Thursday, 26 May 2011 23:14

BULB CHAT JULY 2002 No. 29

THE CHANGING FACES OF FIELD GUIDES

Gladiolus hyalinus : excerpt from a field guide 1926 : -

" A flower which has adopted most thoroughly the through-lighting plan. Viewed from the standpoint of an erect human being the flowers are dull and inconspicuous ; but they are remarkable for the transparency of the lower portion of the broad petal which forms the roof of the flower. Through this the sunlight shines. Stoop down and look into this flower when the sun is behind it. You will be gazing into a miniature scene as brilliant as the cleverest stage artist puts on. Adapt your sense of magnitude and you are in a brilliant and cunningly devised Temple of the Sun."

Now an excerpt from a field guide 1997 :-

" Flowers funnel-shaped, mottled yellowish brown, upper tepal translucent."

NEW BOOKS

The synoptic review of Babiana, including descriptions of ' new species ', is in progress targeted for publication in 2OO3. Another work in progress is a bulb book for the Summer Rainfall Region. Rumour has it that the publishers will only accept it if the Cape Bulb Encyclopedia sells well and it does not look as if that will be published before about November. We also think the revision of Spiloxene is nearing completion. We hope it will include the Australian species but have no firm information on that except that we believe they have been accepted into the genus. We think there will soon be a publication on Tritoniopsis - perhaps in July.

GLADIOLUS WATERMEYERI

The expert on fragrances is expected from Switzerland this spring and particularly wants to see Gladiolus watermeyeri in situ. If you come across a colony please notify Dr J. Manning (( 021 - 799 8660) or Andries de Villiers (( 021 - 558 6537), both of whom will be in touch with him.

Gladiolus watermeyeri is one of the most sought after species of the genus Gladiolus. Growers worldwide are always looking for seed of this plant. The seeds are pinkish to reddish brown and unusually large. No other Gladiolus has seeds like this, which makes it very easy to identify when sowing. These low growing plants are highly fragrant. The flowers are dull mauve, brownish or green. The dorsal tepal is strongly hooded and translucent, while the upper lateral tepals are veined with maroon or pink. Members who have come along on IBSA excursions have seen G watermeyeri to the south of Nieuwoudtville along the road to the Oorlogskloof Nature Reserve. There is also a thriving colony on the top of the Gifberg.

Gladiolus watermeyeri was named after E. B. Watermeyer, a farmer and land surveyor of the Nieuwoudtville district, who collected this plant in 1917. This was not the first collection of this plant. That honour goes to J. F. Drege, who had already made his collection in 1831.

Mrs H.M.L. Bolus described the species in 1927. At that time the corms collected and sent in by E.B. Watermeyer were still in cultivation at Kirstenbosch Botanical Gardens.

EMPODIUM ELONGATUM AND MORAEA OCHROLEUCA

A UK member reports that his lemon-scented empodium, originally from Melmoth (Natal) is markedly light sensitive. On a dull day when the glasshouse temperature reached 26,7 deg the flower did not open. The following day was sunny but cold and windy. The flower opened but closed again when the sun moved off it. His Moraea ochroleuca ( It was collected as Homeria ochroleuca and our member prefers the old name ) survived the winter in the garden at the foot of a south facing wall and flowered.

FLOWERING IN DUTHIASTRUM

Dr. John Manning has responded to the information about Duthiastrum linifolium that appeared in Bulb Chat No 28 and has answered some of the question that were raised.

He writes: The large number of flowers that the writer records on his plants is most interesting. This facility is a function of the particular structure of the inflorescence in this genus (an inflorescence type, incidentally, that has evolved several times among other acaulescent species in several genera, including Ixia and Hesperantha). The inflorescence in Duthiastrum is highly branched with only one flower at the tip of each branch. Obviously, as in many annual plants, favourable growing conditions will extend the life of the plant, allowing further branching to occur and thereby increasing the number of flowers that appear. This is in sharp contrast to other species in which the inflorescence is an unbranched spike. In these species flowering can continue only until all the viable buds have opened on the spike. In her investigations of the inflorescence of Duthiastrum, Miriam de Vos illustrates a plant with 10 buds but 36 is a wonderful number. It is possible that pollination would have curtailed the number of flowers that appeared, much in the way that removing sweetpea flowers extends the flowering period of the plants by delaying depletion of the plants reserves. Turning now to flowering and day length I am afraid that I am less impressed by the extrapolations. The writer neglects to mention a third class of plants, those that are day-neutral. In this group, flowering is independent of day length. I strongly suspect that the majority of our bulbs fall into this category. As evidence I cite my pots, which contain various amaryllids, hyacinths and irids, and which are located on my verandah where they are exposed to light throughout the night from my outside lamp. In day-sensitive plants it is the length of the dark period which determines flowering, not the length of the light period. Breaking a long dark period with short bursts of light, for instance, will prevent flowering in a short-day plant. My pots, therefore, live under constant long-day (=short-night) conditions yet the plants flower regularly at the appropriate seasons.

OXALIS

The genus Oxalis is distributed world-wide, with most of the eight hundred species occurring in South America where they are sub-shrubs or herbs. There are more than 2OO species of Oxalis in South Africa, where they occur mostly in the winter rainfall region of the Western Cape. There are however 16 species that have a wider distribution in South Africa.

Oxalis species are deciduous and either winter- or summer- growing. The bulb is usually deep-seated and the plants are either stemmed or stemless. The flowers are radially symmetric with five petals forming the corolla and five sepals forming the calyx. Compare this with our well known Monocots which have six petals and six sepals.

In South Africa the bulbs of several species are used as food by the indigenous peoples. The bulbs have either to be dried for a few days or roasted well to render them edible. The raw bulbs of some species are used medicinally.

Oxalis pes-caprae and Oxalis caprina are commonly known and are both declared weeds.

Oxalis hirta is an unusual species in that some specimens have a long yellow tube while others have only a short tube. Tepal colours are lilac, magenta or white. The long tubed type was flowering at Gifberg in mid April this year.

TANKWA KAROO

The excursion scheduled for early June fell through because of sickness, but a botanist visiting IBSA's target area about that time reported all flowering either late or reduced because of late rains. However, although very few Moraea speciosa were seen in flower, there were literally hundreds of Tritonia florentiae and Haemanthus tristis in strong bloom. Tritonia florentiae has bright yellow flowers with a bit of red in the throat. They are small plants with a short hidden stem. It is a rarity in cultivation. Only a few of the as yet un-named Babiana were seen. There had been sheep on the ridge where they grow and everything had been heavily cropped. No flowering Lachenalia aurioliae were reported, perhaps also victims of sheep.

IXIA ACAULIS

Also in early June a quite unusually strong flowering occured of Ixia acaulis. The bright yellow and highly fragrant flowers carpetted the ridge on which it grows in the Knersvlakte. Reports both local and from the UK speak of success as pot culture.

This small little Ixia only came to the attention of the Botanists in the early 199O's. It was found growing in rock cracks on limestone ridges in the Knersvlakte. It has a short underground stem, with single, bright yellow, actinomorphic flowers.

COMMON NAMES

I have always mistrusted common names which seemed to me to be liable to change and to be very local. Perhaps I was wrong. In a field guide of 1926 there are " Large Brown Afrikaners", "Brown Afrikaners" and "Small Brown Afrikaners". The names were not new. The Brown Afrikaner - Large also appears in a 19O6 book on South African language usage. The same terms are in the Goldblatt and Manning revision, which seems pretty permanent. But the 1926 guide shows the Large Brown Afrikaner as Gladiolus grandis, the Brown Afrikaner as Gladiolus maculatus and the Small Brown Afrikaner as Gladiolus tenellus. The descriptions (and paintings) are exactly correct. Now the 1926 G. grandis is G liliaceus and the G tenellus

is in fact G hyalinus.Only G maculatus is unchanged. Score 2 to common names and 1 to scientific names!!!

I was led to this comparison by finding 2 Glad. maculatus in flower at the base of the taller Da Gama Cross in the Cape Nature Reserve on 17th June. One was so strongly coloured that it might be described as brown and magenta with the spots golden. The other was yellow with faint red markings. The 1926 field guide warned me of such colour variation.

FLOWERING RESPONSES IN PLANTS

The following is more information on the concept of photoperiodism.

Day-neutral plants flower without regard to photoperiod; that is, daylength has no effect on their flowering. Examples of Day-neutral plants include roses, sunflowers and many weeds.

Short-day plants flower only if light periods are shorter than some critical length. For example, ragweed plants flower only when exposed to 14 hours or less of light per day. Because of their light requirement, Short-day plants usually flower in the Autumn. Asters, dahlias and chrysanthemums are Short-day plants.

Long-day plants usually flower in the Spring or early Summer. They flower only if light periods are longer than a critical length, which is usually 9 - 16 hours. For example, wheat plants flower only when light periods exceed 14 hours. Lettuce, radish and iris are Long-day plants.

Intermediate-day plants flower only when exposed to days of intermediate length; they grow vegetatively if exposed to days that are either too long or too short. Sugarcane is an example

of an Intermediate-day plant.

It was proven by Hamner and Bonner that the length of the Light period was, in fact, unimportant. Plants flowered only if the dark period exceeded 8 hours, regardless of the length of the light period. It was also discovered that flowering did not occur if the dark period was interrupted by a 1-minute pulse of light, even if the regular light period remained less than 15 hours. Hamner and Bonner thus found that flowering requires a specific period of uninterrup-ted Dark rather than uninterrupted light. Thus Short-day plants are more accurately described as Long-night plants, because they only flower if their uninterrupted dark period exceeds a critical length. Similarly, Long-day plants such as lettuce are more accurately described as Short-night plants.

DAYTRIPS

The first trip that you should consider doing at this time of the year is a drive out to Sutherland. On the way there you could stop as you see necessary. The place to stop and to walk further along the road verges is just past the turn-off to the Komsberg at the top of Verlate Kloof Pass

Walk for about 2 to 3 km on both sides of the road. You should see Romulea hallii in full flower now. These plants must rate as one of the most beautiful Romulea species. The flowers are a light blue/lilac colour with prominent yellow markings in the throat.

All along the road at this site you will find the yellow Romulea tortuosa flowering. This is Romulea tortuosa ssp tortuosa - a yellow flower with black markings in the cup. The leaves are extremely curly (tortuose). In cultivation these leaves often become more erect and upright

It is postulated that this happens because of more shade in cultivation. Could this be because it is not as cold in our pots as it is at Sutherland? Are the leaves close to the ground as protection against the severe weather conditions?

At the site you will also find Syringodea unifolia - pale violet to violet/blue flowers.

At this time of the year you will also see Lachenalia congesta as well as Lachenalia undulata here. Looking closely you will also find Romulea atrandra, Hesperantha humilis and an Ixia with sickle shaped leaves at this spot. Unfortunately these plants will only be in leaf at this time of the year. From here you can return to Cape Town via the Komsberg. On the Komsberg road you will see Romulea komsbergensis in leaf. Romulea tortuosa will be flowering all along the Komsberg - sheets of yellow flowers, all hugging the ground. You will see Brunsvigia josephinae in leaf with their very old bulbs about 5O% out of the ground. If you would ever come across these large plants with their grey-green leaves at night you will see that the leaves appear to be white at night when light shines on them. The waxy layer that covers the leaves causes this reflection of the light. The purpose of the wax is to protect the leaves against the harsh sunlight as well as to limit the loss of moisture. It works like a Factor 3O sunblock. Along the Komsberg you can also see Polyxena longituba in the seasonal water logged depressions. There are always Ixias and Moraeas ( M ciliata & M macronyx ) to be seen, mostly still in leaf but the odd plant would have flowers on.

DAYTRIP TO SOUTH OF MALMESBURY

We received a report of a very successful daytrip that a few IBSA members undertook to an area south of Malmesbury. A few km south of Malmesbury a railway track crosses under the N7. Turn off onto the dirt road that runs along the railway track in a westerly direction. Later in the year you will find Gladiolus meliusculus and Geissorhiza monanthos at this turn-off. All along this road you will find Gethyllis ciliaris. There is a township called Chatsworth along this road. Go beyond the houses and you will find more Gethyllis ciliaris as well as Gethyllis afra. Here you will also see Gladiolus carinatus as well as Geissorhiza radians and Geissorhiza euristygma. There are also Lachenalia pallida, L pustulata and L orchioides here. Ixia scillaris was also reported to have been seen here. If you are able to get onto the Dasberg you will find magnificent stands of Lachenalia aloides quadricolor on the granite rocks. Some grow in the fissures, while others grow on the compost collected in depressions in the rock. Lachenalia aloides "tricolor " was also reported to have been seen here this year. Everywhere on the granite boulders there were tall Gladiolus priorii. The Dasberg is on privately owned land, but by all reports the farmer is very friendly. Make time to get his permission to be there.

Later in the year you can also find Gladiolus gracilis and G alatus in this area. Babiana ambigua, B villosula, Moraea neglecta and Spiloxene capensis can also be seen here. Lachenalia unifolia as well as Gladiolus trichonemifolius is also abundant here in September. This is an area worth visiting at any time as you can see, but be warned - do not go alone. Any group of a few people would make it safe, because the locals might want to come and talk to you.

 

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