CATALOGUE. 253 
plants, 2-4’ high, 4-1” thick at base; fertile plants much smaller; flowers 
small, staminate ones 1” wide, lobes ovate-orbicular, acutish; pistillate 
flowers 3-1”, fruit 2’’ long—Only on Pinus contorta, Rocky Mountains to 
Oregon and California; near Breckenridge, at 10,000 feet altitude, Wolf, 
1873. Flowers late in autumn.—In this and the next species, accessory 
flowers or flowering branchlets are developed on the fruiting specimens, in 
this lateral, in the next dorsal to the fruits or fruiting branches. In these 
two we find no other secondary formation on the fertile plants, but in the 
other species sterile branchlets are developed on them which would flower 
in the following year; thus these latter continue their existence for a longer 
time than the two first ones. 3 
ArcrutHosium Dovuetasu, Engelm. ined.—Slender, small, 4-1’ high, 
greenish-yellow, dichotomously branched; branches suberect, single or 
with accessory ones behind the first; flowers in short, usually 5-flowered, 
spikes, staminate ones less than 1” wide, with orbicular-ovate acutish lobes ; 
fruit 24’ long —On Pseudotsuga Douglasit from New Mexico (on Santa Fé 
River, Rothrock, No. 69, 1874) to Utah, Parry, Siler, and Northern Ari- 
zona, Camp Apache, G. K. Gilbert (109), 1873—Flowers May—June.— 
Similar to the last, but smaller, and never with verticillate branchlets or 
flowers, which are so common in that species The thallus-like tissue or 
stroma, which creeps along within the bark of the nurse plant, buds out in 
autumn all along the three years old shoot; after about 12 months, the 
flower-buds are formed, to open in the following spring, after which the life of 
the male plant is exhausted; but it takes another year to perfect the fruit. 
The female parasite, now fully three years old, generally dies, but sometimes 
lives and fructifies another season. The Northeastern A. pusillum, Peck, 
behaves in the same manner, while in A. Americanum and some other 
species the buds of the parasite make their appearance at first only among 
the older bud-scales of the pine branch. : 
Var. ? micRocARPUM is parasitic on Picea Engelmanni, found by Mr. 
Gilbert in 1873 (100 and 102) in the Sierra Blanca, Arizona; it is a. little 
taller, 1-2’ high, but has much smaller fruit, only 1}’’ long, the smallest 
of any American species. 
ARCEUTHOBIUM DIvARICATUM, Engelm. ined. A. campylopodum, var. 
