EUPHORBIA 
382 
Stapelia (Asclepiadaceae). As in the cacti, we get almost spherical 
forms, ridged forms, cylindrical forms, & c. Many are armed with 
thorns. In all cases it is the stem which is fleshy. The outer 
tissue is green and does the assimilating work of the plant ; the inner 
portion of the stem consists mainly of parenchymatous storage tissue. 
The best accessible account of the morphology of E. is that of 
Goebel (. PflanzenbioL Schild . p. 56), from which the following is 
abstracted. He divides the plants roughly into the following groups : 
I. Leaves normal, well developed, serving a long time as assi- 
milative organs. (1) Shoot not water-storing: e.g. the British sp. 
(2) Storage in tubers below ground : E. tuberosa L. (3) Stem as 
reserve for water, &c., but not green: E. bupleurifolia Jacq. (cylin- 
drical stem covered with corky scales = leaf bases. Leaves borne in 
wet season, drop off in dry). (4) Stem fleshy, green, leafy in wet 
season only-: E. neriifolia L., &c. 
II. Leaves abortive, dropping off early. Assimilation and 
storage carried on in stem. Various types occur here (cf. Cactaceae) 
approaching more or less nearly to a perfectly spherical form. Some 
common ones are (1) E. Tirucalli L. (Zanzibar), with thin cylin- 
drical shoots. E. pendula Link is very similar and closely resembles 
Rhipsalis in the Cactaceae. (2) E. xylophylloides Brongn. has flattened 
shoots (cf. Phyllanthus § Xylophytla , and Epiphyllum in Cactaceae). 
(3) E. Caput-Medusae L. has a stout stock giving off a number 
of thinner branches at the top. These are covered with little cushion- 
like papillae, closely crowded, which are really leaf bases ; the leaf 
proper is undeveloped. Many sp. show this structure. (4) E. ma- 
millaris'L. has a thorn injthe axil of each cushion ( = a metamorphosed 
infl.-axis). If the cushions, as in the cacti, become ‘fused,’ we get 
a ridged stem, as is seen in (5) E. polygona Haw. (cf. Echinopsis cerei- 
formis in Cactaceae), E. gra?idicornis and many others. Most of these 
sp. exhibit pairs of stout thorns which are the stipules of the abortive 
leaves. By the two horizontal thorns one can tell one of these plants 
from a cactus, which has a group of thorns. (6) E. meloformis Ait. 
is nearly spherical but ribbed, whilst in (7) E . globosa Sims (cf. 
Echinocactus) we have an almost perfect sphere. [The student should 
read at the same time the art. Cactaceae, and Stapelia, and compare 
all these succulent forms with one another. See also Goebel, loc. cit .] 
Besides the above, mention may be made of E. splendens Boj. and 
E. Bojeri Hook., plants with thick stems and green leaves, the latter 
being dropped in the dry season. 
The other chief point of interest in E. is the cyathium , or infl. 
condensed to simulate a single flr. The resemblance is almost perfect. 
The general branching of the plant is cymose (dichasial). The partial 
infl. forms a cyathium by the non-development of its internodes, the 
absence of the perianths of the individual firs, and the reduction of 
each S flr. to one sta. There is a perianth-like organ of 5 leaves. 
