February 2, 1914 
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Vol. XXVII, pp. 23-28 
PROCEEDINGS 
0.1'' THI': 
BIOLOGICAL SOCIETY OF WASHINGTON 
NEW Sl'ECIES OF OFUNTJA. 
MV DAVID (iUIFFITlIS. 
This Gtli installment* of critical studies in the genus Opuntia 
contains descriptions of new species studied in their natural 
habitat and under cultivation. The tyiies, now in most cases 
at field stations in Texas and California, will in the future he 
deposited in the United States Department of Agriculture. 
Opuntia magna sp. nov. 
A tall opiMi branched, large shrub, or small tree, 2 or M m. or more 
high, and quite symmetrically arborescent, having a distinct cylindrical 
axis which is undivided, and branching perfectly or imperfectly wliorled 
at the apex of previous season’s growth, the trunks 10 cm. or more in 
diameter, strongly tubercular for o or (i years, after that more or less 
smooth and dirty gray-brown; joints cylindrical, dO cm. or more long 
and 4 cm. in diameter, very strongly tubercular, the tubercles being 15 
mm. high and 4 to cm. long, upper and lower curvatures uniform, 
the wliole surrounded by a depressed darkened line separating contiguous 
tubercles; areoles situated on upper slope of tubercles, white, lenticular, 
prominently glandular, turning dirty-gray-hlack in age, 8 mm. long, 
becoming ohovate by formation of new white, glandnlar areolar tissue 
above; leaves 2 to d cm. long, terete, subulate, cuspidate, backward 
curved, tinged with red at tip, 2)^ mm. in diamehu' at base; spicules 
yellow in a small scarcely protruding tuft in upper angle of areole, not 
visible in age; spines reddish-brown with prominent rather gray sheathes 
on current season’s growth, 9 to 15, the lower sloping down and 15 mm. 
long, the 2 lateral just above also sloping down and 10 to 12 mm. long, 
the others shorter and more erect, spreading, not increasing much in 
length in age, but increasing in numbers to dO or 40 on old trunks; 
dowers puri)le; fruit strictly annual, strongly tubercular, subglobo.se to 
hemispherical, deejily cupped at apex,d)0 to d5 mm. in diameter, bearing 
white areoles without visible glands, bearing a triangular tuft of yellow 
* Annual Reports Mo. Rot. Garil. 19-22 : 19U8-1912, and l\r. f. K. 23 : 1913. 
(5—Pkoc. Biol. Soc. Wash., Vol. XXVII, 1914. 
(23) 
