. 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. INFLOBESCENOE. 71 blossoming commences with the central flower and proceeds in order to the circumference, as in the sweet-william, elder, hydrangea. In this kind of inflorescence all the flowers are considered terminal because they do in fact (except the first which terminates the axis) terminate lateral ircmclies successively produced on a definite plan at the node next below the primary flower. 344. Both kinds of infloresc
. 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. INFLOBESCENOE. 71 blossoming commences with the central flower and proceeds in order to the circumference, as in the sweet-william, elder, hydrangea. In this kind of inflorescence all the flowers are considered terminal because they do in fact (except the first which terminates the axis) terminate lateral ircmclies successively produced on a definite plan at the node next below the primary flower. 344. Both kinds of inflorescence are occasionally combined in the samo plant, where the generaZ system may be distinguished fix)m the partial clusters which compose it. Thus in the Compositse, while the florets of each head open centripetally, the general inflorescence is centrifugal, that is, the terminal head is developed before the lateral ones. But in the Labiatas the partial clusters (verticil- asters) open oentriftigally while the general inflorescence is indefinite, proceeding from the base upwards. 345. Of centripetal or axillary inflorescence the principal VARIETIES ARE the spike, spadix, catkin, raceme, corymb, umbel, pani- cle, thyrse, head. ^ 346. The spike is a long rachis with sessile flowers either scattered, clustered, or crowded upon it, as plantain, mullein, vervain. The so- called spikes of the grasses, as wheat, timothy, are in fact compound spikes, bearing little spikes or spikelets in place of single flowers. 347. The spadix is a thick, fleshy rachis with flowers closely sessile or imbedded on it, and usually with a spathe, as in the Arum, or with- out it, as in the 200, Spiranthes cernua; flowers in a twisted spite. 201, Orontium oqnaticum; flowers on a naked spadix. 202, Betula lenta; flowers in aments. 348. The catkin or amentum is a slender, pendant rachis with scaly bracts subtending the naked, sessile flowers, and usually caducous, as in birch, beech, oak, willow. 349.
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