INTRODUCTION XX111 



has a long peduncle and short pedicels ; whilst the Primrose has 

 a very short peduncle buried among its leaves, and long pedicels. 



Among other chief varieties of the inflorescence are the 

 following : — The spike, an elongated axis with sessile flowers as in 

 the Plantains (p. 402). The spadix, a spike with a fleshy axis or 

 peduncle, as in Lords-and-ladies (p. 507). The catkin, generally 

 described as a deciduous spike, as in the Hazel and the Willows 

 (p. 452). The raceme, an elongated axis with stalked flowers, as 

 in Mignonette (p. 60). A corymb, which only differs from a 

 raceme in the lower pedicels being longer, so as to bring all the 

 flowers nearly to a level, as in the Wallflower. A head, in which 

 many small sessile flowers, or florets, as they are called, are 

 crowded together on the expanded apex of the peduncle, which is 

 then termed the common receptacle. This occurs in the Scabious 

 (p. xxii) and in all the great order Composites, the Daisies, Dande- 

 lions, Thistles, &c, which Linnams called " compound flowers." 

 An umbel, in which many flowers-stalks radiate from a common 

 centre, as in the Ivy (p. 225). 



If an inflorescence is branched more than once it is termed 

 compound. Thus an ear of Wheat is a compound spike or spike of 

 spikelets, and the Carrot, Parsnip, Hemlocks, and most other 

 members of the Order Umbellijerce, have compound umbels. 



When the terminal or central flower in a cluster opens first the 

 inflorescence is called a cyme. Among the various forms of cyme 

 are the fascicle, a crowded cluster of nearly sessile flowers, as in the 

 Pinks (p. 71), and the verticillaster or false whorl, where two such 

 clusters occur in the axils of opposite leaves, as in the Dead 

 nettles and other members of the order Labiata (pp. 379 — 401). 



Bracts are small leaves which are generally to be found below 

 the flower. The inflorescence of the Crucijerce is remarkable for 

 being without any, or ebracteate. Sometimes they are mere mem- 

 branous scales, as in the Cranesbills ; or they may be leaf-like, as 

 in the Anemones ; or petaloid, resembling the petals in colour 

 and texture, as in the Wild Hyacinth. When in one or more 

 whorls below the inflorescence they are called the involucre (from 

 the Latin involucrum, an envelope). In the Dandelion the in- 

 volucre consists of two whorls of green bracts, those of the outer 

 whorl reflexed (p. 291). In the Knapweeds the numerous bracts 

 of the involucre are membranous, dark brown, and arranged 

 imbricately, i. e. overlapping like roof-tiles. All Composite and 

 most Umbelltferce have involucres. An involucre persisting in the 

 fruit stage, like the leafy husk of a Hazel-nut or the "cup" of an 

 Acorn, is termed a cupule. This structure gives its name to the 

 Order Cupuliferce. 



