This is the same as the uniparous type of branching and may be scorpioid or helicoid. 283) the stalk of the flower can be distinguished into a peduncle (axis) part and a pedicel (stalk) part with an articulation between the two. When the apical or the axillary bud forms a single flower it does not form a real ‘inflorescence’ but this type is better included within the ‘definite’ group as further development is limited. Inflorescences included herein are the following: 1. This appears as centrifugal where the rachis is flattened to form a receptacle.Ĭymose inflorescences are less common than racemose types. The apical bud is a flower limiting further growth in that direction.Īs this apical bud is the oldest and younger flowers occur below it, the opening of flowers is basipetal (i.e., towards the base). Just as in cymose branching, the growth of the cymose inflorescence is always checked vertically. Here the main axis is branched and several capitula are included within the same involucre as in Echinops echinata of Compositae.
Such difference is found in sunflower but there is no difference among chrysanthemum florets. In some capitula the peripheral or ray florets and the central or disc florets are different in appearance. The whole capitulum is surrounded by an involucre of bracts at the base and each floret usually has its individual scaly bract. The rachis forms a flattened, more or less convex receptacle on which the florets are arranged in a centripetal order. This is the characteristic inflorescence of the family Compositae. many leguminous plants like Acacia, Mimosa, Albizzia (Fig. This differs from capitulum (described below) in having no receptacle. When a large number of sessile flowers grow from a suppressed rachis giving rise to a more or less globose structure, it is termed a capitate inflorescence. The involucres of the secondary umbels are called involucels. Compound umbels arc seen in the garden plant Chaerophyllurn as also in the spices fennel (Foeniculum), coriander (Coriandrum), etc., and also in carrot Daucus carota)-all belonging to the family Umbelliferae (Figs. When the axis of an umbel branches, one gets a compound umbel. In an umbel the central florets are younger and there are involucral bracts. It should be noted that the same inflorescence may change from umbel to corymb and from corymb to raceme due to the elongation of the rachis by growth. The flowers (usually having stalks equal in length) then appear to form a cluster. The umbel differs from the corymb in that the axis is shortened further -almost to nil. When the main axis branches and the flowers are arranged on the branches in a corymbose manner, the inflorescence is a compound corymb as seen in Pyrus torminalis. Similarly, the umbel inflorescence of cherry (Pnams cerasus) may become a corymb when mature. Young inflorescences of mustard look corymbose while they become racemes when mature. This is seen in different species of Cassia. Moreover, the stalks of the flowers are longer and longer as the flower is placed lower and lower on the axis so that all the flowers are placed almost at the same level. In a corymb the axis is not elongated to the same extent as in the previous inflorescences. In maize the male inflorescence bears the paired spikelets in a ‘panicle’ while the paired female spikelets (the lower one of each pair being sterile) are arranged in a ‘spadix’. In wheat, the multi-flowered spikelets are borne on an unbranched axis looking like a compound spike.
This may be described as a panicle of spikelets. In rice, each spikelet is composed of one flower only and the whole inflorescence is branched like a panicle although different from a true panicle. The ultimate inflorescences formed by the spikelets are complex and compound.
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