238 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



" Texas is thought of commonly as a land of Grasses " ; but it is xerophytic 

 nevertheless, illustrated by the 1 Buffalo Grass ' (Bulbilis dactyloides) . 



The author then considers the various plains of Texas and the " Grass 

 formations connected with them," with photographic illustrations. 



Being xerophytic in all species of Grass " the underground parts are 

 reservoirs of food, and not infrequently of water, protected against the 

 extremes of heat and drought to which the arid soil is subjected." They 

 consist of succulent fibrous roots with a thick zone of mucilaginous or 

 saponaceous tissue ; a woody subterranean tuberous caudex ; mucila- 

 ginous bulbs with impervious coats and deep irregular or fusiform roots 

 with hard flinty coats, according to the species, respectively. 



"Mountains and South Plateau Slope" are next considered. With 

 regard to the Grass " A Summary of the Adaptation Features of this 

 Type of Formation " shows : (1) rapid transitions from active to dormant 

 conditions ; (2 ) great resistance to extreme dryness and heat (including 

 fires) while in the dormant stage ; (3) equally great recuperative power 

 after extreme treatment ; (4) large food storage of fats and sugars in 

 portions which retain vitality during dormant periods ; (5) the quality 

 of perfect drying in situ, thus not only covering the soil and holding it in 

 place, but also protecting the vital parts. 



The woody vegetation is then considered, largely based on moisture 

 relations. First are the xerophytic types, as Juniperus sabinoides ; the 

 " Shin " Oak (Quercus breviloba) forms scrub thickets ; and the Qucrcus 

 virginiana, " a dwarfed live Oak," covering lower hill slopes growing on a 

 rubbly soil. 



Then follows a consideration of the semi-xerophytic forests of the 

 high mountain summits. Of these Pinus ponderosa at 9,000 feet, 50 feet 

 high, is the prevalent species. Pseudotsuga taxifolia, Pinus flexilis, P. 

 edulis, Juniperus pachyphlaia, and Oaks of the xerophytic slopes. 



In the lower canons the above dwarfed arborescent species become 

 large trees of regular symmetrical growth. 



From the xerophytic and sub -xerophytic the author passes on to the 

 true mesophytic forest and timber formations, as well as the " Chaparral." 

 This is a shrubby formation of warm, temperate, or semi-tropical type, 

 where there is a minimum of rain, a dry air with great winds, much 

 and intense sunshine, and a loose shifting soil destitute of vegetable 

 mould. The vegetation consists of larger species of Mimosa and forty 

 species of Prosopis. Acacia Fanicsiana prevails on the low moister 

 coast prairie clays, and other species of Acacia are prevalent in other 

 districts. 



After considering different types of Chaparral the author discusses 

 "Formations of Succulent on Water-storage Vegetation." The contrast 

 between this and the preceding formations is that whereas those types 

 had adjusted themselves to xerophytic conditions by retaining the least 

 amount of sap-bearing tissue, this type has gone exactly to the opposite 

 extreme. This type includes the Cactus, the Yucca, and the Agave vege- 

 tation, together with such ephemeral plants as Sedum, Talinum, and 

 Portulaca. 



Next follows a consideration of the rock vegetation of cryptogamous 

 plants. The elements consist of a species of Nostoc, a mat-forming 



