[pbs] Haemanthus--TOW
Mary Sue Ittner
msittner at mcn.org
Mon Dec 6 01:18:19 EST 2004
Dear All,
In the September 2004 Veld & Flora Cameron and Rhoda McMaster published an
article: An assortment of Haemanthus: five species and various forms of
this interesting bulbous plant from the Eastern Cape. Cameron has expanded
this article for an introduction to the topic of the week. He has also
provided 18 new pictures for the wiki of some of the species described in
that article and this introduction. All of our messages have to be in text,
but I have saved his Introduction, which will be in two parts since it is
long, in htm format and will link it on the wiki Haemanthus page for those
of you who might want to print it out with the formatting intact. Here is
the first part:
Haemanthus L. (Amaryllidaceae) TOW
Confined to South Africa and Namibia, the 22 currently known Haemanthus
species are characteristically fleshy, often hairy plants, well known for
their compact, brush-like inflorescences. Their specialised fruits are
berries which contain a few large, moisture-rich seeds. Bulbs of Haemanthus
were amongst the first plants gathered at the Cape and subsequently
cultivated in the gardens of Europe. The earliest known description
appeared in 1605 where plants (probably H. coccineus and H. sanguineus)
were given the phrase name Narcissus Africanus sive Narcissus exoticus. The
name Haemanthus was first proposed by Hermann in 1687 and thereafter
appeared in many publications in the form of Haemanthus africanus. Baker
published a taxonomic treatment of Haemanthus in Flora Capensis (1896),
which included Scadoxus. In a brief review of the genus by Friis and Norval
in 1976, the generic limits of the Haemanthus were amended and the genus
Scadoxus reinstated. As presently circumscribed, Haemanthus includes only
species with true bulbs, distichous fleshy leaves and a chromosome
complement of 16.
The last comprehensive taxanomic treatment of Haemanthus was by Dr Dierdré
Snijman of the Compton Herbarium, Kirstenbosch, Cape Town, published in
1984 (Journal of South African Botany, Supplementary Volume No. 12), from
which much of the information in this introduction is taken. She lists 21
species in this revision and subsequently described one further species
(Haemanthus pauculifolius). Of the 22 species, 14 occur exclusively in the
winter rainfall region with a concentration of species in the dry
Namaqualand region of the North West Cape. Six species occur exclusively in
the summer rainfall region and there are two species which overlap into
both regions, namely H. coccineus which has the widest range extending from
Namaqualand to the Keiskamma River in the Eastern Cape and H. albiflos
which is a summer rainfall species, extending as far west as Still Bay in
the winter rainfall region.
Most species bear two leaves each year. The shape, pubescence, markings and
orientation are valuable taxinomically. In the evergreen species H.
albiflos and H. deformis, leaves persist beyond a year, resulting in 4 to 6
visible leaves. The majority of individuals in H. unifoliatus and H.
nortieri and H. pauculifolius have only a solitary leaf, but in the latter
species, being evergreen, the leaf persists and may exhibit two leaves.
Haemanthus flowers are borne in an umbel surrounded by membranous to fleshy
spathe valves, the position, number and texture of which is taxinomically
important. The fruit is a globose to elliptical berry which when ripe is
soft, pulpy and often translucent varying in colour white, yellow, orange,
red and various shades of pink, depending on the species. The seeds are
succulent, smooth and greenish-white to wine red.
Dr Dee Snijman, in her article "What makes Southern Africas Amaryllidaceae
special" in the IBSA Bulletin No. 42 (1994), describes the seed dispersal
as follows: "When in fruit the scape of Haemanthus elongates and gradually
flops to the ground. The funicle which holds the seed to the fruit wall
produces copious mucilage, aiding germination by protecting the seed from
desiccation. This mode of dispersal is thought to be one in which the seeds
are shed in "safe-sites", namely patches close to the parents suitable
habitat. This strategy maximises the suitability of the niche in which the
seed is deposited which in turn maximises seedling survival. However, the
species ability to spread is limited." It was always a puzzle to me how
plants of H. humilis could become established on almost vertical places
between the rock strata on cliffs where they grow. When handling ripe seed,
we soon realised that this is due to fact that the seeds are connected to
sticky threads that enable them to adhere to virtually any surface and,
under favourable conditions they become rooted seedlings. This feature is
probably common to other cliff growing species.
(to be continued)
Cameron McMaster
africanbulbs at haznet.co.za
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