1914] Fernald and St. John,— Hieracium scabrum 181 
THE VARIETIES OF HIERACIUM SCABRUM. 
M. L. FERNALD AND Hanorp Sr. JOHN. 
On the Magdalen Islands and on Sable Island plants clearly allied 
to the continental Hieracium scabrum Michaux depart in some char- 
acters from the typical H. scabrum, as shown by Michaux's type mate- 
rial and by the common plant extending from Lake Mistassini to the 
mountains of North Carolina. In true H. scabrum the lower internodes 
of the stem, the petioles, and the midribs (beneath) are conspicuously 
clothed with long slender, often sordid, trichomes 2-3 mm. in length, 
while the upper surface of the leaf bears somewhat scattered trichomes 
(on the median cauline leaves 0.5-2. mm. long). The branches of the 
inflorescence and the peduncles are more or less tomentose and heavily 
beset with dark stipitate glands, but neither the tomentum nor the 
glands extend to the lower half of the plant. 
In the Sable Island plant the stem lacks the elongate trichomes and 
is covered, often from base to summit, by a dense pannose white 
tomentum. Numerous short stiff trichomes, barely 1 mm. in length, 
are mixed with the characteristic glands, while both surfaces of the 
leaf are glabrous except for minute, commonly gland-tipped hairs. 
In the branches of its inflorescence and its involucre the Sable Island 
plant closely matches dwarfed, but large-headed, plants of H. scabrum 
and in its fruit-characters seems inseparable from that species. 
On the Magdalen Islands true H. scabrum occurs, but the distinctive 
plant of the region differs in having the lower half of the stem and the 
leaves nearly glabrous or at most with very short sparse trichomes 
(not exceeding 0.5 mm. in length) often mingled with scattered glands. 
A similar and apparently indistinguishable plant is represented in the 
Gray Herbarium from other sections of eastern Quebec and from north- 
central Maine, where it has been collected with typical H. scabrum, 
while all the material seen by us from the north side of Lake Superior 
and the Keweenaw Peninsula of Michigan is of this extreme variant. 
In the course of this study a singular plant from Athens, Illinois, has 
attracted our attention and seems to represent another extreme of 
H. scabrum, in this case tending to an excessive development of slender 
trichomes. In the Athens plant the sordid trichomes of the lower 
half of the stem, the midribs, and both leaf-surfaces are almost uni- 
