﻿148 BOTANICAL GAZETTE [febkuary 



recent years. The pines spread easily without the aid of other plants, but 

 the deciduous trees come up under a cover furnished by roses, plums, and other 

 shrubs ; these in turn are preceded by herbaceous plants. The same author 

 {idem 7:314-319. 1901) discusses the distribution of twenty native forest trees 

 of Nebraska. As Professor Bessey has previously shown, most of these 

 trees have doubtless migrated from the east along the Missouri river ; probably 

 more than fifty species have entered the region in this way, while but ten 

 species have migrated eastward from the mountains. The maps, especially 

 those showing the oaks and hickories, are very suggestive. The author has 

 considered the same subject more fully in another paper (Nebr. State Board 

 of Agric. Ann. Rept, 1899: — . 1900). In the fifteenth annual report of the 

 botanist (1901), entitled "Some Agricultural Possibilities of Western 

 Nebraska," Professor Bessey gives an account of the physical features and 

 the vegetation of the sand hills and foothills. In the sand hills there are 

 twenty-four species of trees, mostly of eastern affinities, and growing chiefly in 

 canons or along the rivers. Forty-eight shrub species occur, twenty of 

 which are of western affinities. The grasses are fully considered. In the 

 foothills there are twenty species of trees occurring on the ridges and m 

 the canons. More western forms (but not a majority) are found than in 

 the sand hills. Professor Bessey (Science 14:185-187. 1901) gave an 

 itinerary for botanists en route to Denver, showing what could be seen from 

 the car window in Nebraska. He also {idem 721-724) wrote concerning the 

 early winter colors of the plant formations on the plains, noting the wide 

 range of color aspects and the color tendencies of various formations, — W. 

 L. Hall (Forester 7:188-193. igoi) tells of the interesting tree planting 

 experiments being made in Nebraska. — J. J. Thornber (Bot. Surv. Neb. V. 

 igoi) has made a statistical study of the prairie-grass formation in region I, 

 near Nebraska City, Physical data of various sorts were collected, phenologi- 

 cal observations were carefully made, and the various habitat-groups were 

 studied. An interesting point brought out in the discussion of ecological 

 factors is the much more favorable light relation in woods than in thickets. 

 The body of the paper is on the structure of the formation, in which the 



w 



controlling species are mentioned in the different habitats. A feature of the 

 paper (wanting in many studies because an account of a region is made 

 as a result of a week's study) is the presentation of the aspect of the 

 prairie, season by season (prevernal, early vernal, late vernal, early estival, 

 late estival, serotinal). A vast number of counts and diagrams of individuals 

 in selected quadrants completes the paper.^ — G. G. Hedgcock {idem VI, 

 1902) has studied the relation of the water content of the soil to certain 

 plants, principally mesophytes. Among other results he finds that plants 

 wilt and die in saline soils, while the per cent, of water is still relatively 

 high, whereas in sand the per cent, of water at which plants wilt or die is 

 lower than in other soils. Seedlings grown in sand are more turgid than 

 those grown in humus. The most watery plants are often the least vigorous^ 





