. Class-book of botany : being outlines of the structure, physiology and classification of plants : with a flora of the United States and Canada. Botany; Botany; Botany. THE OVULES. 109. 415 416 417 414 412 40G, Pistil of Colosia, the pericarp detached showing the young ovules. 413, Flower of Rhu- barb ; pericarp removed showirfg the young ovule. 407. A similar ovule (orthotropous) of Polygonum. 4CN, The same, full grown ; foramen at top. 409, Section showing its two coats, nucleus and sac. 410, Anatropous ovule, as of columbine ; <', foramen. 411, Section of lame. *12, Campylotropous ovule
. Class-book of botany : being outlines of the structure, physiology and classification of plants : with a flora of the United States and Canada. Botany; Botany; Botany. THE OVULES. 109. 415 416 417 414 412 40G, Pistil of Colosia, the pericarp detached showing the young ovules. 413, Flower of Rhu- barb ; pericarp removed showirfg the young ovule. 407. A similar ovule (orthotropous) of Polygonum. 4CN, The same, full grown ; foramen at top. 409, Section showing its two coats, nucleus and sac. 410, Anatropous ovule, as of columbine ; <', foramen. 411, Section of lame. *12, Campylotropous ovule, as of Bean; a, foramen. 414, Section of a cherry, ovule anatropous, suspended. 415, Section of carpel of Ranunculus; ovule ascending. 416, Senecio; ovule erect. 417, Ilippuris; ovule pendulous. 533. The number of ovules in the ovary varies from one to hun- dreds. Thus in buttercups, Composite and grasses the ovule is solitary; in Umbeliferse it is also solitary in each of the two carpels; in tlie Pea Order they are definite, being but few ; in Mullein, Poppy, indefinite{ oo), too many to be readily counted. 534. The position of the ovule in the cell is defined by certain terms as follows; erect, when it grows upwards from the base of the cell, as in Composite ; ascending, when it turns upwards from its point of lateral attachment ;• horizontal, when neither turning upwards nor downwards ; pendulous, when turned downwards, and suspended, when growing directly downwards from the top of the cell, as in birch. (415, 416, 417, 419). 535. The ovule at the time of flowering is soft and pulpy, consisting of a nucleus within two coats, supported on a stalk. The stalk is called funiculus ; the point of its juncture with the base of the nucleus is the chalaza. The nucleus was first formed, then the tegmen or inner coat grew up from the chalaza and covered it, and lastly the outer coat, the trsta, invested the whole. Both coats remain open at the top by a small passage, the micropvle,
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectbotany, bookyear1861
