No. 1. July, 1920] 



KCOLOCY, HAN'T CKOCKAI'IIY 



37 



256. Pbahson, G. A. The relation between spring precipitation and height growth of west- 

 ern yellow pine saplings in Arizona. Jour. Forestry 16 : <»77 689. 8 fig. 1918. -See Hot. 

 Absts. 2, Entries 382, 552. 



257. Petiiybridge, George II. Heterocarpy in Picris echioides. Irish Nat. 28:25-32. 

 PI. S. 1919. — An unknown seed which occurred as an impurity in lucerne seed proved on 

 germination to be Picris echioides. This new seed is described as looking like a "peeled 

 banana" and differs from the usual type. Later studies showed that the flower bead had on 

 the average 67 ligulate flowers; three or four of these situated next the bracts, differed slightly 

 from the others and those produced the peculiar fruit. These two types are referred to as 

 disc and ray florets. The seeds from the ray florets are gripped by the bracts and remain 

 attached to the head after the other seeds have been dispersed by the wind. The suggestion 

 is made thai the whole head may be carried by animals and hence the plant has two methods of 

 seed dispersal. No difference was observable between the plants raised from the two types 

 of seed. — W. E. Praeger. 



258. Pulling, Howard E. Root habit and plant distribution in the far north. Plant 

 World 21:223-233. 1 fig. Sept., 1918. — Describes the root habits of some northern trees. 

 The roots of Picea mariana, Lariz americana, and Betula papyrifera have a rigid shallow 

 root habit, Picea canadensis a flexible shallow habit. Populus balsamifera is deep rooted 

 and flexible, and Pinus banksiana and Pinus strobus have a deep rigid root habit. The 

 degree of flexibility and degree of penetration in deep soils may be a determining factor in 

 the northward distribution of many plants regardless of environmental influences which 

 may exclude other species from those regions. [See Bot. Absts. 2, Entry 288; also rev. by 

 Korstian in Jour. Forestry 17: 327-328.]— Chas. A. Shull. 



259. Rendle, A. B. Some cases of adaptation among plants. Jour. Quekett Microsc. 

 Club 14:23-28. 1919. — Address of president. Primary and secondary adaptations are 

 described in Drosera, orchids, and grasses. It is noted also that there are many forms and 

 structures whose evolution we are quite unable thus far to relate to environment. — H. C. 

 Cowles. 



260. Rigg, George B. Growth of trees in sphagnum. Bot. Gaz. 65: 359-362, Apr., 

 1918. — Data from the Puget Sound region and Alaska show that trees grow very slowly in 

 sphagnum. The western hemlock (Tsuga heterophylla) is the commonest tree in sphagnum 

 in the Puget Sound region, and shows less growth retardation than any other species ob- 

 served. In Alaska bogs conifers growing in Sphagnum are much distorted and frequently 

 are prostrate, while in the bogs about Puget Sound, trees growing in sphagnum are erect 

 though reduced in size. [See Bot. Absts. 1, Entry 193.] — H. C. Cowles. 



261. Sedgwick, L. J. Analyses of some morphological characters of Bombay woody species 

 from an ecological standpoint. Indian Forester 45: 193-199. 1919. — An analysis of the woody 

 species of Bombay as to leaf-apex armature and seed dispersal shows that there is a definite 

 relation between the forms and the environment. 



It is believed that these tendencies are the result of development due to environment. — E. 

 N. Munns. 



