564 ASCLEPIADER® (Brown). [ Xysmalobiwm. 
XII. XYSMALOBIUM, R. Br. 
Calyx 5-partite. Corolla 5-lobed nearly to the base ; lobes sub- 
erect, spreading or reflexed, flat or slightly concave, or the lower 
part very concave and the upper part recurved, overlapping or rarely 
subvalvate in bud. Corona-lobes 5, arising from the staminal 
column opposite the anthers, variable in shape, very thick and fleshy, 
as thick as broad or laterally compressed or dorsally flattened, always 
solid, keelless or with one longitudinal median keel on the inner 
face, never cucullate or complicate, nor with any filiform horn or long 
tongue-like process on the inner face. Staminal colwmn arising 
from the base of the corolla. Anthers terminated by a membranous 
appendage. Pollen-masses solitary in each anther-cell, pendulous, 
attached in pairs to the pollen-carriers by elongated caudicles. Style 
usually shorter than the anther-tips, rarely exserted beyond them. 
Follicles variable in shape, smooth or more or less covered with soft 
bristle-like processes. Seeds crowned with a tuft of hairs. 
Perennial herbs with milky juice and tuberous rootstock or a cluster of thick 
fleshy fusiform roots; stems erect or decumbent, simple or branched at the base, 
sometimes solitary; leaves opposite; umbels few or many and lateral at the 
nodes with 1 or 2 terminal, sessile or pedunculate, or solitary and terminal on a 
long peduncle. 
Distris. Species 38, half of them in Tropical Africa. 
Xysmalobium as understood by recent authors is very unsatisfactorily defined. 
It was separated by Robert Brown from. Asclepias to include those species in 
which the corona-lobes are “fleshy, subrotund, simple on the inner face,” and 
have 5 minute teeth or lobules alternating with them. He referred only 2 
species to the genus, viz.:—Asclepias undulata, Linn., and A. grandiflora, Linn. 
f., which according to modern views cannot both belong to the same genus. As 
the characters given by R. Brown do not at all agree with the structure of A. 
grandiflora, whilst they do roughly accord with that of A. undulata, I take this 
latter as the type of Xysmalobium. The minute alternating lobes are of no 
generic importance, as they are absent from some and present in other species of 
this and many other genera. ‘The definition of the genus as given by Bentham 
and Hooker, and copied in Engler & Prantl, Pflanzenfamilien, does not dis- 
tinguish it from Schizoglosswm, nor apply to all the species, Dr. Schlechter has 
repeatedly asserted that Xysmalobium cannot be distinguished from Asclepias, 
but does not define either genus. In the structure of the corona-lobes, the two 
genera are entirely different, always appearing solid in Xysmaobium, and always 
either cucullate or with a fissure or space between the inflexed sides of them in 
Asclepias. From their fleshy nature it will probably be found that some of the 
descriptions of the corona-lobes do not accord with those organs in living 
flowers, as they alter in the process of drying. 
* Leaves 11-40 times as long as broad, all linear or 
narrowly linear-lanceolate, 4-3 lin. broad, not 
crisped on the margins: 
Corolla reflexed, glabrous on the inner face; 
corona-lobes shorter than the staminal column : 
Anther-wings broadest and distinctly an- 
gular at the middle... it veh ise 
Anther-wings broadest at the base, not at all 
angular at the middle ... ... =... (2) Zeyheri. 
Corolla-lobes erect, with recurved minutely 
velvety tips; corona-lobes overtopping the 
staminal column .., ee om bas ... (3) carinatum, 
(1) involucratum. 
