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PAPEES LOEANTHACEiE. 
ARCEUTHOBIUM. A small genus, represented in S. Europe by a single species, and in America ran- [106] 
ging from the northern border of the United States to Mexico, chiefly in the mountains. 
* Staminate flowers all (or nearly all) terminal on distinct peduncle-like joints, paniculate. 
1. A. Americanum, N'ilU. Slender, dichotomously or verticillately much-branched, greenish yellow ; staminate 
plants sometimes 3 or 4 inches long (J to a line thick at base), fertile plants much smaller; flowers small, the stami- 
nate a line broad or more, with ovate-orbicular acutish lobes, the pistillate a half to one line long : fruit 2 lines long. 
— Engelm. PI. Lindh. 214, and Wheeler’s Rep. vi. 252. 
Only on Finns contorta (and apparently P. Banksiana in the Saskatchewan region), from Wyoming to Oregon 
and southward tcT Colorado and California (Little Yosemite Valley, Bolander). Flowering mostly late in autumn 
apparently, but found by Parry in AVyoming in flower in July ; fruit mature in August and September. Its shoots 
creep along within the tissue of the bark on young branches of the pine, and in the autumn bud cut in the foim of 
little knobs among the bud-scales at the end of three-years-old limbs, developing into flowering plants the next season. 
When once established it may continue to sprout from the same base for many (30 or more) years, causing h>pcr 
trophy of the wood and bark of the limb and often its final destruction. Fruiting and flowering branchlets are often 
seen in juxtaposition in the same whorl, but without leaf-bearing branchlets, and never in superposition. 
The type of the genus, A. Oxycedri, Bieb., of the Old World, is allied to this, but distinguished from it and from 
all American species by its staminate flowers being all terminal on short branchlets and usually in threes, scarcely a 
line wide and with orbicular lobes, and by the much smaller oblong fruit, less than lines long. The northeastern 
A. pusillum, Peck, of the Adirondacks, growing on Ficea nigra, also belongs to this section. 
* Staminate flowers axillary (with a terminal one), forming simple or compound spikes. 
H— Slender, greenish-yellow : accessory branchlets of fruiting specimens flower-bearing. 
2. A. Douglasii, Engelm. Similar to the last, but smaller, J to 1 inch high ; branches suberect, solitary, or 
with accessory ones behind (never beside) the primary ones : flowers in short (usually 5-flowered) spikes ; the stami- 
nate less than a line wide, with orbicular-ovate acutish lobes : iTuit lines long. — Wheeler’s Rep. vi. 253. 
Var. ABIBTINUM, Engelm. A larger form, 1 to 3 inches high (the fertile smaller), with spreading or even 
recurved few-flowered branchlets : staminate flowers Ij lines wide : fruit scarcely 2 lines long. 
On Fseudotsuga Douglasii, from New Mexico to S. Utah and N. Arizona ; the variety on Ahus concolor, in Sierra 
Valley (J. G. Lemmon) and S. Utah, Farry. Flowering apparently in October. Distinguished Irorn the last by its 
usually smaller size, the superimposed (never verticillate) accessory branchlets, lateral flowers, and larger fruit. 
Its creeping stroma buds out all along the branch, and not between the bud-scales only as in the last. Another [107] 
variety, with very small fruit, is found on Ficea Engelmanni in Northern Arizona. 
Stouter, greenish-brown : accessory branchlets. of fruiting specimens mostly leaf-bearing. 
3. A. DIVARICATUM, Engelm. Stouter than the last, 2 to 4 inches high and a line in diameter at base, olive green 
or pale brownish ; branches spreading, often flexuous or recurved : staminate flowers few and scattered or in 3-7- 
flowered spikes, a line wide, with ovate acute lobes : fruit 1^ to 1| lines long. — PI. Wheeler, 1874, 16, and Wheeler’s 
Rep. vi. 253. A. campylopodum, var., Engelm. PI. Lindh. 114. 
On Finns edidis and F. monophylla, from New Mexico and S. Colorado to Arizona and S. Utah, and to be looked 
for on the latter species in S. California. Flowering in August and September. Intermediate in size and color 
between A. Douglasii and the following species, but well characterized by its slender habit, spreading growth, and 
small and rather scanty male flowers. 
4. A. OCCIDENTALE, Engelm. Stout, 2 to 5 inches high, 2 to 2| lines thick at base, paniculately much-branched : 
staminate plants brownish yellow, smaller, the pistillate commonly of a darker olive-brown color ; staminate flowers 
in long dense spikes, often 9 to 17 on a single axis, their buds ventricose with the upper edge curved outward ; calyx 
3-5- (usually 4-) parted, 1| to 2 lines wide ; anthers sessile below the middle of the lanceolate acuminate lobes : fruit 
2i lines long. 
Var. ABIETINUM, Engelm. More spreading and less densely branched, the accessory branches in the fruiting 
plant bearing fertile flowers as often as they do leaf-buds. — A. abietinum, Engelm. Proc. Amer. Acad. viii. 401. 
On various conifers of the Coast Ranges and Sierra Nevada {Finns insignis, F. Sahiniana, and F. ponderosa'), 
from Salinas Valley and Walker’s Basin to Oregon. It is the only American species found also on Jnniperus (Silver 
Mountain, Brewer), The variety occurs on Abies grandis in the valley of the Columbia, Hall. Flowering in August 
and September. 
The closely allied A. vaginatum, Eichler {Viscum vaginatum, HBK.), upon the pines of the Mexican moun- 
tains, of which only incomplete material has been collected, has shorter spikes and smaller mostly 3-parted staminate 
flowers with broader and shorter lobes. A. robustum, Engelm., on Finns ponderosa in the Rocky Mountains and 
Arizona, has shorter spikes than A. occidentale, with shorter flat ap 2 nessed staminate buds, the 3-parted flowers 
