524 BEssEY: STOMATA OF HOLACANTHA 
1854 Dr. Gray described and named it,* referring it provisionally 
to the family Rutaceae, however suggesting its relationship with 
Castala,a genus of Simarubaceae. Good figures of the flowers 
(which are dioecious) are given by Torrey in plate 8 of the “ Report 
on the United States and Mexican Boundary Survey, made under 
the directions of the Secretary of the Interior, by William H. 
Emory” (Washington, 1858), and the genus is referred to the 
Quassia family, Szarubaceac, a disposition which has been con- 
firmed by Bentham & Hooker, Baillon and Engler & Prantl. 
The best description of the genus is still that originally drawn up 
by Dr. Gray, only slight additions having since been found neces- 
sary. The description written some years ago by Dr. Gray for 
the ‘“Synoptical Flora,” and which has but recently been pub- 
lished (June 10, 1897), while concise, is very clear and entirely 
satifactory. 
The plant is locally known as “burro thorn,” “ sacred thorn” 
“crucifixion thorn” and, according to a note in Erythea (March, 
1897) by the Mexicans “ Crucifixo,” and “ Corono de Cristo.” It 
seems, also, that in some way the pseudo-scientific name “ Cruct- 
fera spinosa” has currency among a certain class of people in 
Arizona, and it is used under the impression that it is a good 
botanical name. 
Although described as a shrub, Professor J. W. Toumey, of 
the University of Arizona, assures me in a private letter under 
date of April 25, 1897, that “it reaches the size, and has the 
habit, of a tree on the plains four or five miles south of Maricopa.” 
A photograph, in my possession, of a plant near Phoenix, shows 
it to be a much-branched, spreading shrub, with nothing of a tree- 
like habit. Seedling plants bear small leaves which are described 
by Dr. Gray as ‘‘ lanceolate or linear, half an inch (12 mm.) long; 
thickish, entire or repand, or with a pair of small basal lobes.” 
The mature plant is leafless, nothing more than the smallest scales 
remaining as vestiges. The branches have become modified into 
spreading Nene which are themselves freely branched again. 
* Plantae novae Thurberianae : The characters of'some new genera and species é 
plants in a collection made by George Thurber, Esq., of the late Mexican Boundary 
Commission, chiefly in New Mexico and Sonora. Memoirs American Academ y of : 
Arts and 
iences. II. 5: 297-328. 1854. 
‘cial 
