MELANTHACEA FROM THE GENETIC STANDPOINT. 141 
N. americanum differs from N. ossifragum in (1) much shorter pubescence, 
(2) whole plant smaller, (3) leaf and stem somewhat yellower, (4) one of 
the bracts not above the middle of the pedicel but near its base, (5) corolla 
much paler yellow, (6) anthers yellow instead of vermilion. According to 
Pursh they differ only in (4) the position of the bracts. Comparison of 
herbarium specimens confirms all the above differences except (1) and (6). 
N. americanum is decidedly less stout and more yellowish, while the 
perianth is paler yellow. The difference in the position of the bracts is 
apparently a constant feature, but there appears to be no difference in 
pubescence or in the colour of the anthers *. 
N. californicum is intermediate between N. americanum and N. ossifragum 
in width of leaves, its raceme is rather lax below, and the stamens about 
half the length of the perianth. The filaments are also white-woolly to the 
top, unlike the other three species, in which the summit of the filaments is 
naked. In N. californicum the base of the filaments is frequently naked. 
N. asiaticum I have not seen, but it apparently differs from N. ossifragum in 
having wider leaves (2-3 lines) with conspicuous veins and a longer raceme. 
Examination of a number of specimens shows the following differences 
between N. americanum and N. californicum :— 
N. americanum. N. californicum. 
Leaves usually about 2 mm. wide, 7-9- Leaves about 3-4 mm. wide, 5-7- or 8- 
nerved. nerved. 
Raceme dense, 2:5-8 cm. long. Raceme lax, 7-12 em. long. 
Perianth-segments narrowly linear, 5-6 mm. ^ Perianth-segments oblong-linear, 8-10 mm. 
long, slightly exceeding the stamens. long, considerably exceeding the stamens, 
Plants from the type-locality have orange- 
coloured perianth-segments in fruit. 
Capsules 10-11 mm. long. Capsules 13-15 mm. long. 
Plant 30-40 em. high. Plant 33-60 em. high. 
Hence N. californicum is somewhat larger, though not markedly so, in all 
its parts. The number of leaves in the nerves is often the same, but they 
are farther apart in N. californicum. 
The following specimen in the Herbarium of the California Academy of 
Science is much reduced, and is apparently like the eastern species:— 
Desolation Valley, Lake Tahoe Region, Cal., Louise Hutchinson, Aug. 1909. 
The plant is 2 dm. high, the leaves about 1 mm. wide, 3-4-nerved, 4-5 cm. 
long, the raceme 45 cm. long, perianth-segments 5-6 mm. long, about 
1mm. wide. This raises the question as to whether the differences between 
N. americanum and N. californicum may not be environmentally induced. 
* It is possible, however, that in N. ossifragum there may be a dimorphism in the colour 
of the anthers similar to the condition found by C. H. Danforth in Tiarella cordifolia 
(* Rhodora, xiii. (1911) 192-3). 
