. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. THE SEED-IIABIT 333 plants. As a general rule { most Conifers and Flowering Plants), however, the vascular system of the ovule stops short at its base. The elaborate vascular supply of the early seed- types, as contrasted with the more modern ones, may perhaps be related to the possession of motile spermatozoids, and to the relative degree of exposure and size of the ovules. One important aspect of the permanent retention of the. Fig. igiB.—Reconstrviction of a longitudinal section through the seed of Lyg
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. THE SEED-IIABIT 333 plants. As a general rule { most Conifers and Flowering Plants), however, the vascular system of the ovule stops short at its base. The elaborate vascular supply of the early seed- types, as contrasted with the more modern ones, may perhaps be related to the possession of motile spermatozoids, and to the relative degree of exposure and size of the ovules. One important aspect of the permanent retention of the. Fig. igiB.—Reconstrviction of a longitudinal section through the seed of Lyginopteris oldhamia (after Oliver). Cu., cupule; /., integument; , bundle traversing integument ; m., megaspore ; «., nucellus ; Pc, pollen chamber ; Vb., bundle traversing cupule. megaspore, involving considerable economy, is the possibiUty of postponing the accumulation of food-reserves to a relatively late stage, when fertilisation has taken place and the embryo has begun its development. The embrj-o is, moreover, more ade- quately protected, during its early phases, than is possible in Pteridophyta and Bryophyta, and, after attaining a certain stage, remains dormant and securel}' shielded until conditions arise suitable for its further 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 Fritsch, Felix Eugene, 1879-; Salisbury, E. J. (Edward James), Sir, b. 1886. London, G. Bell and sons ltd.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
