IOWA ACADEMY OF SCIENCES 
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The Lorantliaceae have not been revised by any recent botanist but 
Dr. EngelmaniT has in various papers, described the different species. 
Dr. D. T. MacDougaP has contributed a note on the seed dissemina- 
tion and distribution of Rasoitmofslcya rohustdK 
The Loranthaceac are evergreens which are parasitic upon shrubs or 
trees, they are of a greenish or yellowish green color, are dichotomously 
branched and have stems with sv/ollen joints. The flowers are small and 
inconspicuous; greenish, dioecious; the 2-5 sepals are coherent at the 
base; anthers as many as the sepals and inserted upon them; ovary infer- 
ior, one celled; fruit, a berry with a gelatinous endocarp. 
The genus ArceutlioMum, parasitic on Conifers, has rectangular 
branches and small connate scale-like lea,ves; flowers terminal or ax- 
illary, single or several from the same axil, which often form spikes, 
opening in the summer and maturing fruit the second season. The seeds 
of ArccuthoMum, as those of Phoradendron and the European Yisciim, are 
scattered by birds. In regard to the dissemination of the seeds of Arceu- 
thoMum, Dr. MacDougal states that the single seeded berries are borne 
on short stalks which are curved semi-circularly and from which they 
are easily detached wnen ripe. The berry is joined to the stalk by a 
scission layer, which is ruptured by the slightest touch or may be pressed 
away by the action of forces set up in the berry which also expel the 
seed. The expelling of the seed in this way has been known for many 
years and has found its way into literature. The writer was unable to 
find ripe material to study the m.ethod of its dissemination. The fact that 
Vi^here one tree is affected surrounding trees are usually all, both young 
and old, diseased shows plainly that birds must be an unimportant fac- 
tor in the dissemination of the seed. One may find whole groups or 
patches of affected trees where the ' ArceutfioMum had started at a cen- 
tral point and gradually infected all. A. americanum produces all or 
nearly all of its staminate flowers in terminal distinct peduncle-like joints 
which are more or less paniculate. Staminate plants are dichotomously 
or verticillately branched and are much longer than the fertile ones. 
This is the most destructive species in the Uintah Mountains, sometimes 
covering an area of several acres in extent, w^here in some cases, nearly 
every tree is affected. It is especially noteworthy that where the trees 
occur isolated as after a fire, scattered trees are affected with this para- 
site. It usually attacks the lower branches, but may extend upward pro- 
ducing large fascicled branches which have received the common name of 
“squirrels’ nests” or “witches’ broom.s”. In isolated areas on Black’s 
Fork we found as many as fifty per cent, of the trees were affected, and 
in some cases more than five per cent, had been killed by the parasite. 
A. robustum develops axillary spikes either simple or compound of 
staminate flowers which have short and broad lobes. It is common upon 
1. dray's Plant. Fendl. Mem. Am. Ac. N .5: 4: 1849. 
dray. " I’lant. Lindh. 2: Boston Jonr. Nat. Hist. G; 1850. Trans. Acad. 
Sci. St. Louis. 3: See Bot. Works of the late deorge Engelmann collected for 
Henry Shaw, Esq.. Edited by Trelease & dray. Wheeler’s Rent. U. S. deographi- 
cal Surv. W. of the 100th meridian Botany J. T. Rothrock G: 231. 
Botany California 2: 106. 
2. Minn. Bot. Studies. 2; 1G9 pi. 15, 16 f. 1. 
3. This is referred to by Engelmann as Arcenthohium robustum. 
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