DISTRIBUTION OF TRIBES. 405 
floras. It is closely allied as well to Olearia of the former as to 
Diplostephium of the latter region, differing slightly from both in 
the presence of a few palez on the receptacle. 
(4) The South-American Andine genus Diplostephium, of about 
18 shrubby species, more nearly connected, perhaps, with the 
Australian Olearia than with the American Asters, but with a 
habit and foliage of their own. The achenes are terete or nearly 
so, not flattened as in Aster; and the pappus tends much more 
than in that genus to the shortening of an outer row of sete. 
(5) & (6) Commidendron and Melanodendron, two insular genera, 
the former of three, the latter of a single species, all confined to the 
island of St. Helena, where they may have been originally diffe- 
rentiated from the ancient type of the group, and, like a few others 
of the most ancient St.-Helena plants, appear to have retained 
more of a S.-American (Andine or Western) than of a South- 
African character. Their nearest connexion is with Diplostephium, 
not with Felicia. 
2. The Erigeron type.—Evrigeron, taken in an extended sense, 
has nearly the same geographical range as Aster, but without so 
great a tendency to develop local forms, geographical subgenera, 
sections, or species. It is also, in point of structural characters, 
very closely allied to and blending in with Aster, touching it at 
various points, and passing into it more gradually than the above- 
mentioned semi-geographical genera Felicia, Olearia, Kc. ; and yet 
synantherologists are unanimous in its admission into the ranks 
of genera of the first order. It passes, indeed, quite as gradually 
into Conyza, and thence into other equally large groups, which, 
unless we give up all idea of methodizing, must be admitted as very 
different, although they cannot be strictly defined. "This greater 
blending into allied forms may also not be due to any nearer 
genealogical affinities, but possibly to greater inherent facilities 
for propagation, dispersion, and original intercrossing of breeds. 
The species of Erigeron are in general less distinct from each 
other than those of the Aster type ; and most of them are far more 
widely dispersed ; a few also as annual weeds multiply exceedingly 
wherever they are carried with cultivation, in this respect also 
agreeing more with Conyza than with Aster. To distinguish, 
however, Oonyza and Erigeron from Aster, we have but little 
besides the inerease in number and reduction in size of the female 
florets, which in Zrigeron, although they have still the corollas 
produced into a ligula, have that ligula always very narrow, and 
