524 
than trifoliolate or subpinnate. In flavum they are usually dis- 
tinctly pinnate with 3-7 leaflets, the odd leaflet elongated and ob- 
liquely pinnatifid or pinnately-parted into oblong decurrent lobes; 
the lowest pair of leaflets are frequently also pinnatifid. In the 
trifoliolate stem-leaves of flavum the end leaflet is much longer rel- 
atively to the lateral ones than is the case in Canadense, and the 
simple upper leaves are mostly oblong or narrower with often ob- 
tuse basal lobes, usually in marked contrast with those of Cana- 
dense, which are rhombic-ovate or obovate and cuneate with acu- 
minate or very acute lobes or angles mostly at or above the middle. 
The dentition of the leaves in flavum is coarser than in 
Canadense, especially in the upper leaves, which are very coarsely 
dentate with irregular shallow teeth, in striking contrast with the 
much more finely and acutely dentate-serrate leaves of the latter. 
The stipules of favum are conspicuously larger than those of 
Canadense and variously incised and lobed; an extreme size is 
134’ long by 14’ broad; the largest on specimens of Canadense 
now before me are 8’x 4’. The pubescence of the leaves is in 
flavum coarser and looser than in Canadense, especially along the 
veins on the lower side of the basal leaves; it is much sparser on 
the upper leaves which are sometimes glabrate; in Canadense the 
leaves beneath are finely soft pubescent and velvety to the touch. 
While favum is generally more slender and weaker than Cana- 
dense this is not always true, except perhaps of the inflorescence, 
which is simpler and fewer-flowered with longer, more ascending 
branches and peduncles, the bracts often more foliaceous and 
sometimes entire. 
The flowers of the two plants are always conspicuously different - 
and constitute their most obvious distinctive character. In flavum 
the very small petals are cream-color or palest yellow and much 
shorter than the lobes of the calyx, 1-114” long, 14-1” wide, 
linear-oblong or often broadened to the abrupt or truncate often 
retuse tip; in Canadense they are pure white, oblong or obovate, 
and two to four times as large (2’’-4” long, 114/’-3”” wide) equal-— 
ling or exceeding the calyx-lobes. In both species the anthers 
show a shade more color than the petals. The flowers differ m 
_ further in the sepals, which in Canadense are more accuminate, and — . 
__ inthe bractlets of the calyx, which are rather larger in flavum. In — 
