12 Contributions from the Gray Herbarium 
of the Mexican flora although one or more species may sometime 
be found across the international boundary. The two species of 
Bessera, on the other hand, are peculiar to Mexico and Lower Cali- 
fornia. Altogether it seems best to regard Bessera as a genus dis- 
tinct from Brodiaea even when the latter is considered in its largest 
sense as I have done. 
CaLocHorTus aLBus Dougl. ex Benth. in Maund & Hensl. 
Botanist, ii. t. 98 (1839). C. Englerianus Hort. Berol. Notizbl. 
Bot. Gart. Mus. Berl. ii. 318 (1899). 
Ascherson & Graebner, Synopsis, iii. 218 (1905) have taken up 
the name C. Englerianus for this plant because of the existence of 
the name Fritillaria alba Nutt. Gen. i. 222 (1818), a name which 
refers to another species of Calochortus but which is not to be used. 
Art. 53 of the International Rules states: “When a species is 
moved from one genus into another, its specific epithet must be 
changed if it is already borne by a valid species of that genus.” 
Therefore F. alba must take the name C. Nuttallii T. & G. on being 
transferred to Calochortus because of the presence there of C. albus 
Dougl., a valid species which cannot, according to these rules, be 
renamed C. Englerianus as has been done by Ascherson & Graebner. 
It is well, indeed, that this lovely garden plant may continue to 
be known under the name it has always borne, C. albus Douglas. 
CaLocHorTUsS NANUS (Wood) Piper, Bull. Torr. Club, XXXII. 
537 (1906). C. elegans Pursh, var. nanus Wood, Proc. Acad. Phil. 
168 (1868). 
When Piper, 1. ¢., raised this plant to specific rank he wrote: 
“‘ This species is nearer true C. elegans Pursh than any other Cali- 
fornian species.” C. elegans does not grow in California, as indeed 
Piper himself indicated, 1. c. 540. In fact, C. nanus appears to 
me to be related much more closely to C. coeruleus (Kell.) Wats. 
than to C. elegans. It has the fimbriately ciliate petals of the 
former and so far as I can see is indistinguishable except by the 
acuminate anthers. The anthers of typical C. coeruleus are rounded 
at apex but tipped with a more or less obvious apiculation. There 
are, however, several collections which seem to indicate that this : 
difference in the anthers is not always constant and if in future 
more material proves this to be the case C. nanus can scarcely be 
kept as a species distinct from C. coeruleus. Two of the specimens 
referred by Piper without question to C. nanus appear intermediate 
