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. The botanical class-book, and flora of Pennsylvania, designed for seminaries of learning and private classes. eloping inthe one way. Thus the heads of all the Composite are cen-tripetal, the flowers expanding regularly from the margin orcircumference to the centre; while the branches that bear theheads are developed in the centrifugal mode, the terminal orcentral heads first coming into flower. This is exactly rever-sed in all the Labiatse (plants of the mint tribe,) where thestem developes in the centripetal mode, and the axillary clus-ters of the flowers being produced in the form of a gen
. The botanical class-book, and flora of Pennsylvania, designed for seminaries of learning and private classes. eloping inthe one way. Thus the heads of all the Composite are cen-tripetal, the flowers expanding regularly from the margin orcircumference to the centre; while the branches that bear theheads are developed in the centrifugal mode, the terminal orcentral heads first coming into flower. This is exactly rever-sed in all the Labiatse (plants of the mint tribe,) where thestem developes in the centripetal mode, and the axillary clus-ters of the flowers being produced in the form of a generalraceme or spike, which blossoms from below upwards; whilethe flowers from each cluster form a cyme, and expand in thecentrifugal manner.—Gray. 162. The following are the principal varieties of centri-petal inflorescence—the spike, raceme, corymb, umbel, head,spadix, ament, panicle, and thyrse. 163. Spike (Fig. 75,) is an inflorescence, where the ses-sile flowers in the axils of the bracts are arranged along an INFLORESCENCE. 55 elongated commom peduncle, as in the Plantain, Vervein,Mullein. 75.
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Keywords: ., bookcentury1800, bookdecade, booksubjectbotany, booksubjectplants