1917] Pease,— Is Aster tardiflorus a Hybrid ? 89 
i. Color of Stem. 
ii. Pubescence of 
Stem. 
iii. Shape of 
Leaves. 
iv. Serration 
v. Inflorescence. 
vi. Height of In- 
volucre. 
vii. Involucral 
Bracts. 
viii. Color of 
Rays. 
ix. Length of 
Rays. 
cordifolius [green or purple.| 
tardiflorus [green or purple.| 
| puniceus usually purple below. 
) 
cordifolius nearly glabrous (but var. Furbishiae 
Fernald densely villous). 
fardiflorus glabrous or subpubescent (but var. 
vestitus Fernald densely villous). 
puniceus rough hairy in lines [but a variety from 
| northern Maine densely villous]. 
cordifolius cordate, the lower on slender and 
naked ciliate petioles. 
tardiflorus ovate- or oblong-lanceolate, narrowed 
at both ends, the lower to a winged 
[often ciliate] petiole, not auriculate 
or only obscurely so. 
puniceus oblong-lanceolate or lanceolate, not 
narrowed or but slightly so to the 
auricled base. 
All three have leaves sharply serrate in the middle. 
In all three paniculate. 
cordifolius 4-6 mm. 
tardiflorus 5-7 mm. 
puniceus 7-12 mm. 
cordifolius appressed, tipped with short green 
points, obtuse or acutish [ca. 3- 
seriate]. 
tardiflorus lax, linear or linear-subulate, subequal 
or 2-3-seriate. 
puniceus loose, thin, narrowly linear, attenuate, 
subequal, in about 2 rows, the outer 
sometimes foliaceous. 
tardiflorus light blue. 
| cordifolius pale blue or nearly white. 
puniceus lilac-blue to white. 
( cordifolius [rather short, for the genus. | 
l tardiflorus [short to medium.] 
puniceus long and showy. 
