. Morphology of gymnosperms. Gymnosperms; Plant morphology. 324 MORPHOLOGY OF GYMNOSPEBUVLS In a study of the ovuliferous bracts of Saxegothaea and Micro- cachrys, Thomson (164) has discovered an inverse orientation of the vascular bundle supplying the ovule, a feature which has been used to prove the double nature of the ovuliferous structure in Pina- ceae. The same in- version, however, occurs in the supply bundle for the microsporan- gium, which is evidently borne upon a simple sporophyll. Among the Abietineae, Taxodineae, and Cupressineae, how- ever, there is a double inversion in the ovul
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 324 MORPHOLOGY OF GYMNOSPEBUVLS In a study of the ovuliferous bracts of Saxegothaea and Micro- cachrys, Thomson (164) has discovered an inverse orientation of the vascular bundle supplying the ovule, a feature which has been used to prove the double nature of the ovuliferous structure in Pina- ceae. The same in- version, however, occurs in the supply bundle for the microsporan- gium, which is evidently borne upon a simple sporophyll. Among the Abietineae, Taxodineae, and Cupressineae, how- ever, there is a double inversion in the ovulif- erous structure, one related to the sporangial supply, and the other presumably related to the modified dwarf shoot; while among the Araucarineae only the sporangial inversion oc- curs. The conclusion is that among the Tax- aceae and Araucarineae the ovuliferous structure is a simple megasporo- phyll; while among the Abietineae, Taxodineae, and Cupressineae it is. Fig. 378.—Ovulate structures of various conifers: I, Agathis australis, ovuliferous scale from inner side (M, winged seed); 2, longitudinal section of i; 3, Araucaria excelsa, longitudinal section of scale, etc., also showing the outgrowth (i) above the seed; 4, Cunninghamia sinensis, ovuliferous scale, showing three ovules (M), and an outgrowth (i); 5, Micro- cachrys tetragona, longitudinal section of ovuliferous scale, also showing the arillus (o) and the outgrowth (i); 6, Cryptomeria japonica, longitudinal section of part of the strobilus; 7, 8, Cupressus Lawsoniana, showing a young cone (7) and a later stage (8); p, Podocarpus macrophylla, longitudinal section, showing ovulate structures and aril {ar).—From Engler and Prantl's Nat. Pflanzenfam. a double structure. The developmental periods of the ovules of the Taxaceae have not been obtained in so many cases as among Pinaceae. In Torreya taxifolia (loi) the ovulate strobilus is first apparent late in July (in Florida), the mother cells appear during the au
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