' q 
S20 Achenial Hairs and Fibers of Composite. | January, i 
writers, and running on the lines of the general affinities of the — 
groups. = 
The achenial hairs of Seneczo vulgaris and of Doria (Othonna} 
long ago attracted interest; they are double, each having two — 
tubes with a partition between, like the two flues of a double = 
chimney, and they contain within their interior spiral fibers or 
elaters which are rapidly unwound on the access of moisture, ~ 
swelling and escaping by the tips of the ~ 
tubes, as by the lifting of a pair of trap- | 
doors (Fig. 1). l 
I have found that other species of the 
genus Senecio have similar hairs. S. vis- 
cosus L., is represented by De Candolle and — 
by Hooker and Arnott as having glabrous — 
J achenes ; and S. żriangularis of Colorado is 4 
Le similarly described by Porter and Coulter. 
But both these species have duplex achenial ~ 
Fic. 1. — Duplex hair s 4 
froin aes of Senecio vul]. hairs with elaters, though less conspicuous — 
afa: the elaters pro- than in S. vułgaris; and the same is true of — 
the two varieties of S. aureus, balsamita 7 
and borealis. The duplex hairs abound most on the angles of the : 
achenes, and are mounted on a pedestal consisting of a pair ot 4 
cells apposed like the guard-cells of a stomate. : 
The achenial hairs of Ruckeria, belonging to the sub-order_ 
Calendulaceze, were shown nearly half a century ago, by Decaisne, 
to agree with those of Senecio. In examining other genera of the 
Calendulacez, I find that in some cases the achenes are glabrous, - 
and that Calendula arvensis has multicellular hairs on its achenes 
like those of the perianth. This I take to be a case of the ens | 
croaching of perianth hairs on a neighboring region, which occurs — 
in a number of genera; there being still room for an intermediate _ 
set of duplex hairs. I believe that I have found 
these in Calendula, though not so clearly as to 
make out its affinity with Senecionide (Fig. 2). 
In the sub-order Inuloideæ the achenial hairs are — 
—Mul duplex and obtuse, and mounted on pedestal-cells, — 
like those of Senecio, but devoid of elaters. They 
manifestly represent the elater-bearing hairs already 
described, and one is tempted to think that they 
must have shed the elaters, but we have found no traces of such 
structures even in young flow ars (Fig. $) 
