PORTULACEX, AND THEIR ALLIES. 59 
delimitation, which, indeed, have not met with general adoption. 
The disturbance of the ordinary alternation in the different whorls 
composing the flower is curious in several Caryophyllee, without 
our being able to detect any cause or to trace any connexion with 
other characters: thus the styles are opposite the sepals in Ceras- 
tium, alternate with them in Sagina, and when exceptionally pen- 
tagynous, as in S. aquatica, in Stellaria. The stamens, when 
reduced to 5, are usually opposite the sepals, but alternate with 
them in Colobanthus, without however being epipetalous or accom- 
panied by any other of the characters of Portulace» ; and, again, 
in Schiedea, so nearly allied in most respects to Stellaria, and 
having both series of stamens present in their usual position, the 
petals are opposite the sepals, which does not occur in any other 
genus of the Curvembryonous group. 1t has been endeavoured 
to explain this circumstance by calling the petals staminodia or 
sterile filaments ; but that does not remove the difficulty ; for when 
staminodia do exist in any allied order, they are not, any more 
than petals, placed as in SeAiedea. 
The Portulacez, as we should continue to limit them, have been 
generally recognized as a natural group. They are more or less 
succulent. The leaves are alternate or occasionally opposite, but 
never perhaps so strictly so as in Caryophylles ; the petals either 
very fugacious or shrinking very soon into a withered mass, which 
makes it very difficult in some of the minute-flowered species to 
ascertain their number or shape from dried specimens. All genera, 
except Portulaca itself, are essentially hypogynous ; and in Portu- 
laca, where the ovary is half-inferior, the ring bearing the petals and 
stamens is as closely connected with the ovary as with the calyx ; so 
that if, as has been suggested, the adherent base of the flower be con- 
sidered as an enlarged concave torus or summit of the pedicel, the 
insertion of the petals in Portulaca may be said to be less truly 
perigynous than in those Alsiuez where they proceed from a disk 
lining the base of the calyx and free from the ovary. We there- 
fore have no hesitation in following A. Gray and others, who rank 
Portulaceze among Thalamiflore. The ovary in Portulacaria is 
uniovulate, and becomes an indehiscent 3-winged nest; and in 
Silvea the fruit is a 1-seeded utriele; but in both genera the 
flowers are too decidedly Portulaceous to remove them from the 
family, 
The Tetragoniez and Sesuvieæ, united by Fenzl with Portu- 
lacez, differ both from them and from Caryophyllee in their 
ovary divided into cells, and in their very perigynous stamens. 
