ARIOPSIS 
248 
Ariopsis T* Grah. Araceae (vi). 1 sp. E. Ind., A . pcltata J. G., 
a small tuberous herb with hood -like spathes whose openings face 
downwards so that the firs, are protected from rain &c. The 
few ? firs, are at the base of the spadix, the <f above. This part 
is full of round holes leading into pear-shaped cavities surrounded 
each by a synandrium of 6-8 sta. The synandria are fused to each 
other so that the surface of the spadix is continuous from the opening 
of one fir. to that of the next. 
Arisaema Mart. Araceae (vii). 50 sp. As., Abyss., N. Am. Like 
Arum, but dioecious. It is said to be fertilised by snails (ct, 
Alocasia). 
Arisarum (Tourn.) Targ. Araceae (vii). 3 sp. Medit. 
Aristea Soland. Iridaceae (11). 14 sp. S. Afr., Madag. 
Aristida Linn. Gramineae (vm). 100 sp. temp, and sub-trop. 
Aristolochia Tourn. Aristolochiaceae. 180 sp. trop. and temp. They 
are herbs with rhizomes, or twining lianes. Of the latter A. Gigas 
Lindl., the pelican flower, is often grown in hot-houses for the sake 
of its enormous firs. Many trop. sp. have a small leaf surrounding the 
stem at the base of each ordinary leaf, and looking like a stipule. This 
is really the first leaf of the axillary shoot, which grows very rapidly 
at first. In other cases this leaf remains small and its shoot does not 
develope, so that it looks like an interpetiolar stipule. In most sp. 
several buds are formed in each leaf axil ; the firs, usually come from 
the upper ones. 
A. Cleviatitis L. (birthwort) occurs as an escape in Brit. The 
perianth is tubular, hooded at top, and enlarged below round the 
gynostemium; this has 6 sessile extrorse anthers below and as many 
stigmatic lobes above (these are really not the true stigmas, but the 
connectives of the anthers, which have assumed stigmatic functions). 
The young fir. stands erect and the perianth-tube contains numerous 
hairs, which are jointed at the base in such a way that they can easily 
be bent downwards but not upwards. There is no honey. Small 
flies enter the fir. at this stage and find the stigmas ’ripe, so that 
if they bear pollen from other firs, fertilisation takes place. They are 
unable to escape until in the course of a day or two the pollen is shed, 
and then the hairs wither, the fir. at the same time bending down- 
wards (cf. Arum). In A. Sipho L’Herit. (Dutchman’s pipe) ,the 
perianth is bent like a siphon and has a polished interior surface. 
The mechanism of all A. wants further investigation. It seems 
probable that there is a large amount of self-fertilisation. 
Aristolochiaceae. Dicotyledons (Archichl. Aristolochiales). 5 gen. 
with 200 sp., trop. and warm temp., except Austr. Herbs or shrubs, 
in the latter case usually twining lianes. Leaves alt., stalked, often 
cordate, usually simple, exstipulate. Fir. $ , epigynous, regular or 
zygomorphic. P. usually (3), petaloid. Sta. 6 — 36, free, or united 
with the style into a gynostemium (cf. Asclepiads, Orchids &c.). 
