. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 225 the greatest amount of work has been done in fixing juvenile forms, such relatively permanent forms being known in cultivation as species of Reiinospora. While some of the adult forms of Cupressineae, as Juniperus communis, retain the habit of spreading needles, others develop concrescent leaves upon their adult shoots, that is, leaves whose adaxial faces have become organically connected with the adjacent stem surface, so that they appear as green scales. In such cases, the juvenile form, with its spreading
. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 225 the greatest amount of work has been done in fixing juvenile forms, such relatively permanent forms being known in cultivation as species of Reiinospora. While some of the adult forms of Cupressineae, as Juniperus communis, retain the habit of spreading needles, others develop concrescent leaves upon their adult shoots, that is, leaves whose adaxial faces have become organically connected with the adjacent stem surface, so that they appear as green scales. In such cases, the juvenile form, with its spreading needle leaves, presents a striking contrast with the adult form (fig. 256). In shoots from stumps or wounds, the juvenile form of leaf has been observed in Pinus, Thuja, and Taxodium, a response quite in harmony with Jeffrey's in- terpretation of the appearance of resin ducts as a traumatic response. The juvenile forms of Sciadopitys, like those of Pinus, produce simple needle leaves upon long shoots, but later, scales appear instead of needles, and in their axils the peculiar double needle leaves are developed. GoEBEL suggests that the juvenile form prol^ably repre- sents the more primitive form. It is certainly true that if the adult bodies of many of the forms, not mentioned above, be associated with these juvenile forms, a very consistent body is discovered for Pinaceae (and for Conif- erales). It would follow that the replacement of fohage leaves. Fig. 254.—Araucaria excelsa: a specimen in the Washington Park (Chicago) 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; Chamberlain, Charles Joseph, b. 1863; Coulter, John Merle, 1851-1928. Morphology of spermatophytes. Part I. Gymnosperms. Chicago, University of Chicago Press
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