10 
CONTRIBUTIONS TO BOTANY. 
sidered as composed of two or more paleae united by their mar- 
gins into a dentate tube, as is shown in the last whorls, where 
these tubes are quite free from one another. In Calycera the 
capitulum is seated upon a long scape, the leaves being radical ; 
in Acicarpha, and frequently in Boopis, where the plant has many 
branching leafy stems, a capitulum issues from each alternate 
axil, upon a rather short peduncle. In Anomocarpus, in three 
species, the capitula are nearly sessile in the remote dichotomy 
of the branchlets ; while in another species the axis of the plant 
is so completely depressed that aU the leaves become radical, 
with its numerous sessile capitula interspersed between them, so 
that the whole grows into a pulviuate shape with a crowded 
mass of flowers. In Nasianthus all the species assume a some- 
what similar form, from an aggregation of its numerous capitula, 
each supported upon a very thick fleshy peduncle, which bears a 
single leaf near its summit, a little below the level of the invo- 
lucre. 
In regard to the natural affinities of the Calyceracem, nearly 
all systematic botanists are agreed in following the indications 
first suggested by the illustrious founder of the order, who 
showed that its closest alliance is with the Compositce ; it has 
consequently been regarded as holding an intermediate position 
between that family and the Dipsacece, with which it also accords 
in its capitate involucrated inflorescence, its monopetalous co- 
rolla, its inferior 1-celled ovary with an adnate calyx, its undi- 
vided style and simple stigma, and its solitary suspended ovule, 
— its fruit being likewise a monosperm ous achaenium, crowned 
by the persistent teeth of the calyx, and the embryo of its seed 
imbedded in an ample albumen. It differs, however, from the 
Dipsacem in the peculiar venation of the corolla, in having its 
filaments united at the base into a monadelphous ring, and in 
its combined half-syngenesious anthers. 
i\Ir. B. Clarke * first proposed to separate these families, by 
some distance, in a natural system founded principally on the 
normal position of the carpels and the relation of the raphe to 
the placenta. Under his arrangement, in the monopetalous 
proterocarpous division of Exogens, he places the Calyceracea in 
his Tetragonal alliance with Valerianacece and Dipsacece, while 
Compositce appear in his Myrtal alliance, the Onagrarial alliance 
being interposed betw^een them. It is needless to say that the 
grounds of arrangement in this system are most feeble, as the 
more important considerations of floral and carpological struc- 
ture, as well as general habit, are completely placed out of view. 
* Ann. Nat. Hist. 2 ser. xi. 454-456 
