. A textbook of botany for colleges and universities ... Botany. 73S ECOLOGY tallest individual forms. Sequoia and Eucalyptus, occur in much drier regions. ^Maximum diametral increase occurs, on the whole, in rela- tively arid climates. It is sometimes stated that the baobab, a xero- phytic African tree, has the greatest diametral growth of all known trees; other xerophytic trees with great diametral enlargement are the dragon tree {Dracaena Draco) and CaianiUesia. However, some trees of great diameter (as the redwood and the hemlock) are meso- phytic. Probably trees are a relatively recent pr
. A textbook of botany for colleges and universities ... Botany. 73S ECOLOGY tallest individual forms. Sequoia and Eucalyptus, occur in much drier regions. ^Maximum diametral increase occurs, on the whole, in rela- tively arid climates. It is sometimes stated that the baobab, a xero- phytic African tree, has the greatest diametral growth of all known trees; other xerophytic trees with great diametral enlargement are the dragon tree {Dracaena Draco) and CaianiUesia. However, some trees of great diameter (as the redwood and the hemlock) are meso- phytic. Probably trees are a relatively recent product of evolution, and doubdess the tree habit has originated many times and in many habi-. FlG. 1060. — The mountain sheep (Raoulia crjiM/d), a remarkable alpine composite, illustrating the culmination of the cushion habit among seed plants; each coral-like colony is composed of thousands of separate but closely compacted shoots, the whole ma^ being attached to solid rock by a single root system; New Zealand. — From Cockayne. tats. Sometimes it has been assumed that the tree habit is a result of the "struggle for existence" in mesophytic climates: this, per- haps, is a tenable view, since growth in dense cultures increases stem elongation. However, there is equal reason for believing that trees have arisen also in dn- regions, since lignification and diametral en- largement are best developed there. Perhaps the most essential step in the evolution of the tree habit is in the passage from an herb to a shrub; if so. experiments on such plants as Spiraea salicifolia and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928; Barnes, Charles Reid, 1858-1910, joint author; Cowles, Henry Chandler, 1869- joint author. New York, Cincinnati [etc] American book company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
