380 MR. G. BENTHAM ON COMPOSITE. 
but sometimes imbricate in several rows, very generally more or 
less herbaceous, but sometimes dry and rigid or membranous, 
very rarely the inner ones scarious. The capitula are most fre- 
quently heterogamous, with a single row of female and fertile or 
neutral and sterile florets in the circumference, the disk-florets 
fertile or in some subtribes uniformly sterile. In some genera 
also the capitula are (by the imperfection rather than by the 
absence of the male or female organs) strictly unisexual, either 
monoecious or dicecious ; and sometimes the capitula are homoga- 
mous from the deficiency of the ray-florets. The fertile florets 
are uniformly subtended, and sometimes embraced by or enclosed 
in the pales of the receptacle or innermost bracts of the involucre. 
These pale: are deficient only in the centre of the capitulum in 
the subtribe Milleriez,, where the disk-florets are always sterile, 
and in some Madiez, where they are frequently so. The corollas 
of the outer female or neutral florets are usually ligulate and tri- 
merous, very rarely with an irregularly campanulate limb, or 
shortly tubular; in the subtribe Ambrosiez they are reduced to 
a short conical tube or entirely deficient ; the corollas of the disk 
with five, or rarely four, short lobes or teeth; in a very few small 
genera there is a slight tendency to the bilabiate form, either by 
the development of one or two small fine upper lobes to the ray- 
florets, or by an irregularity in the disk-florets. These disk-florets 
are generally yellow, sometimes white, rarely purple; the rays 
usually homochromous. The anthers have the normal terminal 
appendage, except in Eleutheranthera and possibly a few species 
of allied genera; and in the Ambrosiee these appendages termi- 
nate in inflected points; the basal auricles sometimes very short 
and obtuse, are more frequently acute, and sometimes produced 
into short points, which have been termed tails. The anther-tube, 
as a whole, is in many genera much exserted and black. The styles 
of the fertile disk-florets vary in different genera, from the trun- 
cate tips of Senecio to the appendiculate branches of Asteroidez, 
or the subulate hispid branches of Vernoniaces. As in other 
tribes, the style remains undivided in the disk-florets of most 
genera where they are constantly sterile. The achenes are often 
rather large, either thick and hard or sometimes even succulent, 
or laterally or dorsally flattened and sometimes winged. The 
pappus most frequently consists of two or three rigid awns or 
scales corresponding, and often continuous, with the principal 
ribs or angles of the achene, with or without smaller interme- 
