A New Species of Othonna (Compositae) from Southern Namaqualand (South Africa)
by John Lavranos
Some time ago Guy Wrinkle, of Los Angeles, California, drew my attention to an interesting
dwarf Othonna which he had encountered near the small town of Nieuwerus, in
southern Namaqualand. Some specimens were secured in time and it became apparent
at once that it represented an unrecorded species.
(click photo to magnify)
Nieuwerus lies only a relatively short distance beyond the northern boundary of
the celebrated Knersvlakte, home of an incredible concentration of succulent species
and, while conditions to the north of this do not look as promising, it had been
long known that a wealth of interesting plants grew there as well. Their habitat
had simply been overshadowed by the huge diversity of the flora further south, with
the result that this area had received relatively little attention.
The southern reaches of Namaqualand are made up of a sandy coastal plain along
the cold South Atlantic, backed to the east by a 50-100 kin wide tract of hills composed
mainly of granites and gneisses with lesser expanses of schists and quartzites, separated
by small, sandy valleys. Here it rains in the southern winter, about 70% of the meager
annual average of 150-206 nun rain falling from April to September, with most of
between June and August. Summers are generally dry and hot, although heavy local
thunderstorms can occur; the temperatures are usually elevated, highs of more than
40 'C being quite common. The proximity of the cold Benguela current along the coast
renders the western section of these hills subject to frequent fluctuations of temperature,
with warm spells alternating with cool ones, dependent on whether the winds are from
the eastern or from the western sector. In the latter case, fog and low cloud is
a frequent phenomenon overnight.
The soils are sandy or gravelly, with a very low organic content. In some of the
hills they are skeletal, the situation being often aggravated by unreasonable grazing
practices, whereby small livestock, mainly sheep but also goats, are run in numbers
at times far exceeding the carrying capacity of the land. The vegetation consists
largely of low woody shrublets, the Compositae and Zygophyllaceae being particularly
well represented. Succulents are fairly numerous, with the Mesembryanthemaceae being
by far the most abundant, as they are in the Knersvlakte where, however, their numbers
both by way of individual and species concentrations are far greater. Trees and tall
shrubs are infrequent, with species of Rhus (Anacardiaceae) being the most conspicuous,
but some of the ephemeral water courses exhibit a fringe of the thorn-tree, Acacia
karroo. As elsewhere in the South African and Namibian winter rainfall regions, areas
densely covered with milky quartz chips and, in particular, those underlain at shallow
depths by compact bodies of this rock, invariably harbour a diversity of species
higher than that observed in adjacent sandy tracts or slopes of granitic or schistose
The new species here described was found on one of the quartzite patches which
does not exceed a couple of hectres (approximately 5 acres) in extent, where, it
grew with many other succulent species, such as Aloe krapohliana, Tylecodon pearsonii,
T reticulatus, a Monilaria with lovely salmon or orange-pink flowers, several species
of Crassula, a few bulbs, principally Homeria (Iridaceae), Albuca and Ornithogalum
(Liliaceae) and a species of Gethyllis (Amaryllidaceae). It is with pleasure that
I am dedicating this species to Guy Wrinkle, who brought it to my notice.
Othonna wrinkleana Lavranos, nov. sp., affinis 0. lepidocauli, sed abilla
basibus foliorum vaginantibus, detate squamosis, valde maioribus latioribusque, caulein
fere amplectentibus differt. Holotypus: D. Geldenhuis sub Lavranos 31141, Africa
Australis, Provincia Caput Bonae Spei austro-occidentalis, prope pagum Nieuwerus,
in clivis saxosis quartziticis, MO (holo), STE & P (iso). Nomen speciei repertorem.
illae, Guy Wrinkle, commemorat.
Description: A low, single stemmed or sparingly branched, erect, succulent plant.
Stem to 50 (70,= tall, 1015 nim thick. Leaves deciduous, up to about 12 in number,
curicate with a rounded and sometimes slightly indented or minutely apiculate apex,
20-40(-60) min long, 15-22 mm wide, flat or slightly convex, obscurely veined, gray-green,
their margins entire, the lamina narrowing gradually to a thickened base, 2-3 mm
wide, which abruptly expands into a broad sheath which clasps and almost spans the
girth of the stem and then persists in the form of a rounded, slightly emarginate
scale that is yellowish at first, turning brown and then dark gray with age.
Peduncles terminal, 1-4 from the same apex, produced successively, erect, 30-70(-120)
min long, 1-2 turn thick, rather wiry, 2-12-branched near the apex, each branch subtended
by a small, hairy bract or, occasionally, by a small leaf. Capitula radiate, with
bright yellow florets, the involucre broadly campanulate, 4-6 mm wide, the 8 involucral
bracts uniseriate, ovate oblong with an acute apex, green, 4-5 min long, 1.0-1.3
mm broad, basally connate; receptacle convex, shallowly honeycombed, minutely woolly.
Ray-florets mostly 8 but occasionally 7, female, fertile, the tube 1.0-1.5 mm long,
somewhat flattened, the lamina ovate oblong, 5-7 turn long, 1.5-3.0 turn broad, 5-6-veined,
the apex indented to irregularly three-toothed, the style short, terete, divergently
2-branched, the tips rounded. Achenes ovate with an obtuse apex, ca. 3 min long,
1.2-1.7 mm. broad, densely and shortly white-woolly, the pappus-bristles numerous,
in several series, persistent, white, 1-2 mm long. Disc-florets 12-20, the corolla
glabrous, ca. 3 mm long, the tube carnpanulate, ca. 2 min long, the lobes broadly
ovate-triangular, 1 mm, long; anthers 2.5 mm long; style terete, sterile, with a
simple, swollen, papillate tip, the pappus-bristles numerous, white.
0. wrinkleana belongs to the group of species that comprises 0. hallii
Nordenstam, 0. lepidocaulis Schlechter, 0. retrorsa D. C. and certain others. It
seems to be most closely related to the second of these, but differs from it in its
leaves, which are much wider and never bear marginal lobes and, above all, in the
scales which cover its steins. These are wide and almost embrace the entire width
of the stem; they also tend to become emarginate and change in colour with age, from
yellow to dark brown to blackish-gray. In 0. lepidocaulis the scales are small, rounded,
chestnut-brown or lighter in colour, giving the stem the appearance of an elongated,
The species grows on a gentle slope, covered with milky quartz fragments. It appears
to be rare and I am told that it was not noted on similar looking places in the same
area. This being the case, it has been decided not to divulge its precise habitat.
The above article is copyright ©Piante Grasse (Journal of the Italian Association of Succulent Plants),