Xysmalobiuma. | LXXXV. ASCLEPIADEZ (BROWN). 299 
in the bud. Corona-lobes 5, arising from the staminal-column and 
opposite the anthers, variously shaped, very fleshy, sometimes as thick 
as broad or laterally compressed, with or without keels or teeth on 
their inner face, sometimes dorsally flattened, but then comparatively 
thick and entirely without keels or with only 1 rather stout longi- 
tudinal median keel on their inner face, solid, never cucullate or com- 
plicate, nor produced into a terminal horn, sometimes with 5 
minute teeth or rudimentary lobes alternating with them at their base. 
Anthers terminated by a membranous appendage. Pollen masses 
pendulous, solitary in each anther-cell, attached to the pollen-carriers 
in pairs by elongated caudicles. Style usually shorter than the anther- 
tips, rarely exserted beyond them. Follicles variable in shape, smooth 
or softly echinate. Seeds crowned with a tuft of hairs.—Perennial 
herbs with milky juice and tuberous rootstock or roots. Stems 
erect, rarely diffuse, usually simple and often solitary, but sometimes 
much branched at the base. Leaves opposite. Umbels sessile or 
pedunculate, solitary and terminal, or most of them lateral between the 
bases of the petioles, and one or two terminal. 
Species many, extending into South Africa. 
Xysmalobium as hitherto defined is very ambiguous in character, and by the 
definitions given cannot be distinguished from Asclepias and Schizoglossum. 
Originally it was separated from Asclepias by R. Brown to include those species 
which have 5 minute lobules or teeth alternating with the 5 coronal-lobes, without 
giving importance to other characters. R. Brown only refers two species to it, viz., 
Asclepias undulata, Linn., and A. grandiflora, Linn. f., two plants, which accord- 
ing to modern views, cannot well be placed in the same genus. The minute alter- 
nating lobules, although of specific value, are not of generic importance, since they 
are present in Xysmalobium decipiens, N. E. Br., and absent in the closely allied 
X. Holubii, Scott-Elliot. In Asclepias also there are some species with, others 
without them. Bentham & Hooker distinguish Xysmalobium by the following 
character, “ coronal-scales flat, unappendaged,” but this character neither applies to 
all the species of Xysmalobium, nor distinguishes it from Schizoglossum. This 
absence of a definite distinguishing character has led to much confusion during 
recent years; even the same species is referred to another genus by the same or a 
different author. Undoubtedly Xysmalobium, Asclepias, and Schizoglossum are but 
artificial divisions of one natural genus, since they cannot be separated by characters 
that do not break down at some point, yet as there are 3 types of coronal structure 
in the group, it seems undesirable to follow Baillon, who in his “Histoire des 
Plantes,” x. 226, unites them, or Schlechter, who in the “Journal of Botany,” 1896, 
451 (without assigning reasons), unites Xysmalobium with Asclepias, retains Schizo- 
glossum and refers some species, which I cannot separate from Xysmalobium, to 
other genera. Therefore in dealing with the Tropical African species of this group 
T have sorted them as follows : 
_ All species in which the coronal-lobes are cucullate or more or less com- 
plicate or cleft on the inner face, are laterally compressed or at least measure as 
much from front to back as they do in breadth, with or witout a horn or other 
Process in the cavity, and are never dorsally flattened, I refer to ASCLEPIAS. 
All species in which the coronal-lobes are dorsally flattened, or if concave 
or with incurved edges, then always broader than they measure from front to back, 
usually with 2 slight or wing-like parallel keels and with or without 1 or more horns 
or other appendages on the inner face, and are never laterally compressed, cucullate 
or complicate, or with a single median keel, I refer to ScHIZOGLOSSUM. 
