SOUTH AMERICAN PLANTS. 73 
Before concluding these remarks, I will offer some further 
observations upon the genera constituting the suborder Rec- 
tembryee, among which I have noticed a feature hitherto 
unobserved, and although not universal among all the genera, it 
offers in most cases a very decided character; I allude to 
the position of the ovarium upon a well-marked and distinct 
columnar support. In Petunia and Nicotiana the ovarium 
is sessile upon an annular disc, which surrounds and conceals 
this support: in Petunia this disc is 2-lobed, in Nicotiana 
it is generally 4-lobed. In Metternichia itis sessile,* without 
any glandular appendage. Among those possessing a stipitate 
ovarium, Fubiana has 2 oblong erect free glands, fixed on 
the column, while in Veséia an annular ring invests the 
stipes and supports the ovarium. In Nierembergia, Sessea, and 
Cestrum, (including Habrothamnus), the column is simple, 
quite free, and generally without any glandular appendage, 
or at least one that is not always easily perceptible. In 
Sessea, Cestrum, Vestia, Nierembergia, and Petunia, the tube 
of the corolla is circumscissile, leaving a persistent cupuli- 
form base that, in some cases, nearly incloses the ovarium, 
a character I have before pointed out, as existing in some of 
the Nolanacee. 
I have observed also in the Rectembryee, that the surface 
of the testa in the seeds affords a variable character: in 
Metternichia and Sessea, it is chartaceous; in Cestrum, mi- 
nutely reticulated and favose ; in Vestia, broadly rugose, 
with fine transverse strie; in Nierembergia, with polished 
prominent ruge ; and in Fabiana, it is nearly smooth, with 
almost imperceptible, longitudinal, rugose strie. In Petunia 
it is divided into large, equal, hexagonal hollows, separated 
by simple ridges, while in Nicotiana these ridges are waving, 
crenulate, or even sometimes cristate when viewed by a 
powerful lens. 
The pollen grains of Metternichia and Sessea are spherical, 
with 3 rounded mammiform equidistant points, and 3 inter- 
mediate convergent lines; those of Cestrum, Fabiana and 
* This, however, is only apparently so, as the column is of the same 
thickness as the ovarium. 
L 
