. Morphology of gymnosperms. Gymnosperms; Plant morphology. 322 MORPHOLOGY OF GYMNOSPERMS (150) it is made up of spirally arranged and imbricated bracts that form an ovoid cone, and in Microcachrys a definite strobilus is formed by the sporophylls, which occur in decussating cycles of four and thus give the appearance of a spiral arrangement. The case of Torreya taxi folia (lOi) may illustrate the general situation. In this form the strobili are borne in the axils of the lower leaves of short young shoots, usually a pair of them on a short axil- lary branch. In most cases there is only a singl
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 322 MORPHOLOGY OF GYMNOSPERMS (150) it is made up of spirally arranged and imbricated bracts that form an ovoid cone, and in Microcachrys a definite strobilus is formed by the sporophylls, which occur in decussating cycles of four and thus give the appearance of a spiral arrangement. The case of Torreya taxi folia (lOi) may illustrate the general situation. In this form the strobili are borne in the axils of the lower leaves of short young shoots, usually a pair of them on a short axil- lary branch. In most cases there is only a single pair of strobili on a strobiliferous shoot, but frequently there are two pairs, and rarely three on the same shoot. Therefore, near the base of these shoots two to six strobili may occur, the upper pairs never maturing and usually only one of the lowest pair producing the large plumlike seed (fig. 376). A strobilus consists of four en- veloping bracts and a single, terminal, erect ovule, resem- bling a simple ovulate flower with a perianth of four bracts; but these are evidently the sterile bracts of a much re- duced strobilus. The relation of the strobili to the young shoot is exactly comparable to the arrangement of the staminate strobili, the difference being that more of the latter mature and the stamens are numerous. In this sense, the whole ovuliferous shoot may be regarded as corresponding to the compound ovulate strobilus of the Abietineae. A general feature of Taxaceae, illustrated by Torreya, is the. Fig. 376.—Torreya taxifolia: ovulate branch, April 7, 1904; natural size.—^After CoTJLTEE and Land (ioi).. 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. Gy
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