36 NATURAL HISTORY OF PLANTS. 
ment, and an anther with two sublateral cells independent of each 
other towards the two extremities, and dehiscing towards the edges 
or a little outwards by two longitudinal clefts. The gynæceum is 
inserted at the bottom of the receptacle, in the 
concavity of which it is partly lodged; it is com- 
posed of a unilocular ovary, the short eccentric 
style having a tendency to become gynobasic, and 
being crowned by a stigmatiferous penicillate apex. 
In the interior is a single ovule, subbasilar, ereet 
and amphitropous, with the micropyle turned 
downwards and from the side of the back of the 
earpel.' The fruit is an unsymmetrical achene, narrow and elongated, 
accompanied at its base by the erect perianth and the persistent fila- 
ments of the stamens, while on the side are found the remnants of the 
style.” It is surmounted by from four to six prickles inserted in its 
upper part, and which existed upon the ovary where they were ascen- 
dent, while here they are, in hardening, reflexed upon the pericarp. The 
seed is suberect, narrow, folded upon itself towards the middle of its 
length in the same way as the embryo,* whose cotyledons have their 
apex turned back towards the radicle, which is inferior. These 
cotyledons are very unequal; that which touches the radicle being 
longer and narrower and having reflexed edges, while the other, by 
which it is enveloped, and whose edges are inflexed, is much thicker 
andshorter. A little mass of albumen accompanies the embryo, placed 
towards the edges and in the intervals of the two folded parts. The 
Petiverias are undershrubs of tropical America. There are two or 
three species‘ of them. All their parts have an alliaceous odour. 
Their leaves are alternate, simple, entire, petiolate, accompanied by 
two small lateral stipules. Their flowers are in terminal or axillary 
racemes, but which seem at first to be spikes, so short and thick are 
their pedicels ; each is placed in the axil of a bract, and bears at a 
variable height two sterile bractlets. 
Petiveria alliacea. 

Fie. 52. 
Flower (2). 
1 

1 It has two coats, and its endostome of the fruit, which is found where the remains of 
forms a long opening which penetrates across the 
exostome to the outside, and presents a narrow 
aperture at its swollen apex. 
2 Its form is comparable to that of a grain of 
oats; it bears also on one side a longitudinal 
mesial groove, finished aboye by a slope; but 
this does not correspond to the organic apex 
the style is seen, 
3 Described wrongly by Moqurn (Prodr., xiii. 
sect. ii, 4) as straight; it is folded upon itself more 
tightly still than that of other plants of the same 
group. 
* Gom., Obs., (1803), 13.—Fiscn. et Mry., 
Ind. Sem. Hort. Petrop. (1835), 35: 
