ASCLEP/ADEX (Brown). 519 
processes ; stigmatic cavities below the angles of the style-apex, 
behind the fissures between the anther-wings. Ovules numerous or 
very rarely few or solitary, anatropous, pendulous, imbricate in 
several series on the projecting placenta. Fruit of 2 follicles or by 
abortion of 1, variable in form, smooth, echinate or winged, opening 
by the ventral suture and usually liberating the placenta. Seeds 
usually numerous, very rarely few or solitary, imbricate, flat or 
cochleate, usually with a broad or narrow margin, crowned with a 
tuft of long silky hairs at one end, or rarely densely fringed all 
round, very rarely without a tuft of hairs; testa rather thick, sub- 
crustaceous or sometimes thin; albumen usually thin or none, 
rarely thick; embryo straight or rarely slightly curved, usually 
nearly or quite filling the seed; cotyledons flat; radicle superior. 
Erect, prostrate, twining or scrambling herbs or shrubs, with milky or watery 
juice ; stems simple or branched, sometimes leafless or with very minute leaves, 
then often succulent, with terete or angular branches, often toothed or spiny at the 
angles ; leaves opposite or whorled, rarely alternate, thin, coriaceous or fleshy ; 
flowers very variable in size and form, solitary or few or many together in 
umbels, umbel-like cymes, fascicles or racemes, axillary, more or less lateral 
between the bases of the leaves, or terminal. 
Distris. An Order of over 1,800 species widely spread throughout the 
Tropical and Sub-tropical regions; a few in the Temperate regions. 
The Order is well marked by the peculiar structure of its pollen apparatus, 
coronal-appendages and stigma, but in other characters it is allied to Apocy- 
nacee. In having the pollen-contents of each anther-cell united into a waxy 
mass attached by caudicles in pairs to the pollen-carriers, it is unique among 
Dicotyledons, and resembles the Orchidee among the Monocotyledons. ‘The 
5 stigmas or stigmatic cavities correspond to only 2 carpels, are com pletely 
hidden from view behind the anther-wings, and can only be seen by careful 
dissection or by making transverse sections of the dilated part of the style ; 
the only openings to the stigmas (except in the tribe Periplocee) are the 5 narrow 
fissures formed by the contiguous anther-wings. No other Order has a similar 
structure, a detailed account of which, as well as the manner of fertilization, has 
been given by T. H. Corry (Trans. Linn. Soc. ser. 2, Bot. ii. 75, and 173, tt. 16, 
24-26). All previous authors seem not to have understood this structure and 
have erroneously described the style-apex as the stigma. The pollen-carrier is 
also described as a gland, which it is not, in any sense of the word, but a hard, 
horny, elastic structure. The Asclepiadee are a very difficult group to study, 
and no unknown member of the Order can be generically determined until the 
character and position of the pollen as seen seated iu place in the anther-cells, 
not as withdrawn, have been first ascertained. By the pollen the Order may 
readily be divided into distinct primary groups:—(1) Granular and loosely 
contained in the more or less spathulate entire or bitid pollen-carriers, but not 
attached to the latter (Periplocew).—(2) United into very minute waxy masses, 
4 or 2 of which are sessile upon a very minute quadrate pale-coloured pollen- 
carrier (Secamonex).—(3) United into waxy masses, which are opaque (or rarely 
with a pellucid area or linear space at one end or on the inner margin, and thea 
distinctly pendulous), usually not very minute, and attached in pairs by caudicles 
to dark-coloured pollen-carriers (Cynanchew with pendulons polleu-masses, 
and Marsdeniee with erect or horizontal pollen-masses ; Tylophora is inter- 
mediate between these two tribes, having minute pollen-masses that are some- 
times pendulous, sometimes horizontal).—(4) United into waxy masses, which 
are pellucid along one margin or just beneath the apex and attached in pairs by 
eaudicles to dark-coloured pollen-carriers, erect, ascending or horizontal, never 
pendulous (Ceropegiee and Stapeliee). : : 
In the following descriptions, the dimensions of the dried flowers I have 
