290 
CONTRIBUTIONS TO BOTANY. 
almost agglomerated : the leaves are very small, ovate, or oblong, 
fleshy, nerveless, and obsoletely toothed on their margin, taper- 
ing into a short petiole ; they are 1^ line long, 1 line broad, in 
opposite pairs upon a slender nascent shoot about | inch long. 
From the axils and the articulations of the spines a short sprout 
is seen, bearing a few leaves and two or four flowers, which are 
almost fasciculated ; the pedicels are a full line long ; the cylin- 
drical tube of the calyx is 1^ line long, with four segments of a 
quarter their length ; the petals are like small white scales, inter- 
mediate with the segments, and only a quarter of their length ; 
the anthers are like those of the preceding species ; the ovary 
and style are glabrous. The flowers are pale when dried, and are 
probably nearly of a white colour when fresh*. 
7. Trevoa. 
This genus, first proposed by me (in 1825), was afterwards de- 
scribed by Sir William Hooker (in 1830), in the ‘Botanical Mis- 
cellany,^ where it is confounded with Talguenea ; he subsequently 
(in 1 833) suppressed the genus, referring the plant on which it 
was founded to Retamilia, because of its indehiscent fi’uit. In 
Trevoa, however, we have a tree of very hard wood, spreading into 
numerous thick tortuous branches, and equally tortuous branch- 
lets, which are very spiny, with an abundant foliage, offering a 
strong contrast to the bare Ephedra-like branches of Retamilia. 
In Trevoa the calj'x is persistent, does not enlarge, but remains 
withered, enthe, and membranaceous, at the base of its fleshy 
drupe ; while in Retamilia the whole of the calyx falls away, 
leaving its short stipitate torus (or small adnate disk) to support 
a much larger globular fruit. The form of the calyx is also dis- 
similar in the two genera, and the petals are larger and more cu- 
cullate. In the species on which I founded the genus, the ovary 
is uniformly bilocular, producing a small 2-celled fruit, often by 
abortion 1 -locular : another species, which Sir "William Hooker 
had inferred to be identical with mine, has a 3-celled ovary, pro- 
ducing a larger 3-celled nut, which circumstance induced that 
distinguished botanist to merge the genus into Retamilia ; but the 
characters above mentioned are sufficient to keep them distinct. 
There is, however, another distinguishing feature in the shape of 
the stipules, which in Trevoa are deeply bifid, forming a small 
fuscous linear kind of wing attached to each side of the petiole, 
of nearly equal length, by which they are attached to the stem ; 
and the bases of the opposite petioles are connected on each side 
by a transverse line across the stem. 
By other botanists Trevoa has been confounded with Talguenea ; 
* This plant is shown in Plate 39 f. 
