A MONOGRAPH OF THE HAUYEAE AND GONGYLOCAR- 
PEAE, TRIBES OF THE ONAGRACEAE, 
By Joun Donne. Samira and J. N. Ross. 
INTRODUCTION. 
A recent study of the genus Hauya, native of the mountains of 
Mexico and Central America, has led to the discovery of a new 
species and has shown that an outlying species, Hauya arborea, from 
the desert of Lower California, must be excluded and made the type 
of a new genus. The differences between Hauya and the new genus, 
here named Xylonagra, are so numerous that one feels the need of 
calling attention less to these than to the points they have in com- 
mon which are requisite to keep them in the same tribe. Herbarium 
work on the group has been supplemented by field work on the part 
of Dr. Rose, who studied Xylonagra on Cedros Island and brought 
back a large number of herbarium specimens. 
During his visit to Lower California Dr. Rose collected material of 
another species of the Onagraceae, which has been referred wrongly 
to the genus Gongylocarpus. This, too, proves to be of a new 
generic type, here named Burragea, which with Gongylocarpus forms 
a new tribe. 
SYSTEMATIC TREATMENT. 
Tribe HAUYEAE Raim.! 
Calyx tube long-produced above the ovary, cylindrical, deciduous, the segments 
4, elongated, reflexed in anthesis; petals 4, inserted at the apex of the calyx tube, 
sessile; stamens 8, inserted with the petals; filaments subulate or filiform, the anthers 
linear, versatile; ovary 4-locular, the ovules few or very numerous, affixed to the 
interior angle of the cells, ascending; capsule oblong, ligneous, loculicidal, the valves 
4, septiferous in the middle; seeds few or very numerous, ascending, imbricate, 
obliquely produced upward into a subcartilaginous wing. 
Trees or shrubs; leaves alternate, petiolate, simple, entire; flowers solitary or 12 
leafy racemes. 
Hauya was made the type of the tribe Hauyeae by Raimann, it being the only 
genus. As treated here, the tribe contains Hauya and Xylonagra. 
KEY TO THE GENERA. 
Arborescent; leaves large; flowers large, few, axillary; seeds 
biseriate.........----- 2-22 e eee eee eee eee ee eee eee 1. Havya (p. 288). 
A dwarf shrub; leaves small; flowers minute, numerous, in a 
terminal, leafy-bracted raceme; seeds uniseriate..... 2. XYLONAGRA (p. 294). 
1 In Engl. & Prantl, Pflanzenfam. 37: 211. 1893. 987 
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