96 Rhodora [May 
In order properly to orient the small-leaved boreal series here spe- 
cially considered, the leading features of ihe other sections of the 
genus represented in eastern America are indicated in the key. 
a. Basal leaves! erect, oblanceolate to elliptic-acuminate, 2-16 
cm. long, similar to the cauline ones: involucres of the pistil- 
late heads brown to blackish: plants sparingly to not at all 
stoloniferous. 
A. eucosma Fernald & Wiegand and A. pulcherrima (Hook.) Greene. 
a. Basal leaves spreading, forming depressed rosettes, strongly 
contrasting in outline with the cauline leaves: plants 
humifuse or freely stoloniferous b. 
b. Larger basal leaves only 1.5-5 mm. wide, blunt or barely 
short-mucronate c. 
c. All the involucral bracts of the pistillate heads? deep- 
brown, drab or blackish d. 
d. Bracts subequal, narrow; the inner linear or lanceolate 
and acute: heads 1-6 e. 
e. Rosette-leaves terminated by a short but distinct 
glabrous mucro: corollas 3.5-5 mm. long f. 
f. Rosette-leaves glabrous and  bright-green or 
grayish-pubescent above: cauline leaves dis- 
tant; the upper with an oblong glabrous scarious 
appendage: corollas 4-5 mm. long: pits of the 
denuded receptacle 20-30, 0.3-0.4 mm. broad, 
much broader than the intermediate ridges....1. A. alpina. 
f. Rosette-leaves canescent: cauline leaves crowded; 
the upper with a lanceolate pubescent scarious 
appendage: corollas 3.5-4 mm. long: pits of 
denuded receptacle 60-100, 0.1 mm. broad, 
about as wide as the blunt-edged intermediate 
WSOC Wc. soe a T MENU 2. A. Sornborgeri. 
e. Rosette-leaves canescent, blunt, the terminal mucro 
obsolete or in old weather-worn leaves barely 
visible: corollas 3-4 mm. long g. 
g. Cauline leaves 9-15; the median and upper taper- 
ing to a slender subulate tip; only the very 
uppermost with a lanceolate scarious appendage. .3. A. cana. 
g. Cauline leaves 5-8; all but the lowermost with an 
oblong-lanceolate flat scarious tip 1.5-3 mm. 
i n. i P ee S nee 4. A. vewillifera. 
d. Bracts in about 5 outwardly shorter series, oblong, 
obtuse: head solitary......................... 5. A. pygmaea. 
c. At least the inner bracts of the pistillate heads with 
white or whitish tips: basal leaves whitened above 
with minute pubescence h. 
h. The 1-3 uppermost cauline leaves with slender scarious 
terminal appendages: rosette-leaves blunt or short- 
mucronate: pistillate involucres 4-7 mm. high, with 
appressed-ascending bracts 7. 
i. Involucre of 4-6 series of distinctly unequal pale- . 
brown DIRE; i o e esie nae e e ia E i 6. A. straminea. 
1 By basal leaves are meant not only those of the basal rosette but the new broad 
leaves terminating the stolons or basal offshoots. On account of weathering the for- 
mer are often bruised and uncharacteristic. 
The only species of this series of which staminate plants are known is A. nitida. 
The descriptions of all the others, therefore, are drawn only from pistillate plants. 
e RM SOC T. - CW.A—-— We K 5 ` 
