172 A GENETIC STUDY OF NORTH AMERICAN MELANTHACE.E. 
In California, from Shasta Co. to Napa and Amador Co., chiefly in the 
Sacramento Valley. Said to be rare. 
Specimens: Near Napa, Calif., A. W. Robinson, 1892. Redding, Shasta 
Co., California, A. A. Heller, May 26, 1905. 
Odontostomum, while most nearly related to the group of Chlorogalez, is 
rather isolated, especially in flower-structure, though the foliage and habit 
clearly resemble that group. Of the three genera it is nearest Chlorogalum. 
The flowers are small and yellowish and the base of the stem forms a fibrous- 
coated corm. The deciduous perianth of Odontostomum in the form of a 
cylindrical 12-nerved tube, bearing in salver-form and finally reflexed the 
5-nerved segments, is a new feature in this group. Our experience of 
mutations is as yet too limited to permit an understanding of the way 
in which the development of this organ took place. The perianth-segments 
are obtuse and the three outer ones cucullate at the tip. 
Another striking peculiarity is in the stamens. There are 6 stamens with 
subglobose anthers at the summit of short filaments, and alternating with 
them are 6 staminodia, the whole forming a ring at the top of the perianth- 
tube*. In this feature Odontostomum bears some resemblance to the 
Mexican Hemiphylacus, though in the latter there are only 3 stamens and 
3 (longer) staminodia. Evidently several definite variations occurred to 
produce the Odontostomum flower, but what their sequence has been it is 
impossible to say. In connection with the stamens there has evidently been 
a loss mutation in Hemiphylacus (see p. 170), while there must have been a 
positive mutation in Odontostomum. 
The fact of parallel mutations introduces an important principle into 
conceptions of phylogeny. Thus Chlorogalum and its relatives have versatile 
anthers, but it is not necessary to assume that this feature has been handed 
down from a common ancestor of Chlorogalumand Lilium. It is much more 
probable that the versatile condition has been developed independently in the 
Chlorogaleæ and the Lilieze through parallel mutations. 
KEY TO MAP, PLATE 5. 
GENERA OF Melanthacee. 
. Tofieldia. 2. Triantha. 3. Pleea. 4. Narthecium. 5, Xerophyllum. 6, Helonias. 
7. Chamwlirium. — 8. Amianthium., 9. Scheenocaulon. — 10. Stenanthium. 
11. Stenanthella. 12. Zigadenus. 13. Anticlea, 14. Toxicoscordion. 15. Oceanorus, 
16. Melanthium. 17. Veratrum. 18. Schcnolirion, 19. Hastingsia. 20. Chloro- 
galum, 21. Odontostomum. 
* According to Jepson [in Fl. W. Mid. Calif. (1901) 114  * the stamen opposite the lower 
outer segment stands alone and faces the remaining 5, which approximate each other by 
their filaments on the upper side of the flower.” 
