THE INFLORESCENCE 



77 



bracts ( "prophylls" ) on the peduncle. Species of the section Nosphinium 

 of Viola — woody shrubs of Hawaii — have a cyme with two to four 

 flowers. In other sections cleistogamous or vestigial flowers are described 

 as present in the axils of the bracts. The related genus, Hybanthus, with 

 various forms of inflorescence, shows similar reduction to solitary flowers. 



The inflorescence of prominent genera of the Proteaceae — Banksia, 

 Grevillea — shows flowers arranged in pairs in longitudinal rows, each 

 pair subtended by a single bract. Comparative and anatomical study 

 shows that each pair represents two surviving flowers of a lateral 

 racemose cluster which has been shortened until the axis is buried 

 within the cortex of the main axis. Stages in this reduction are present 

 in the more primitive genera, Macadamia and HicksbeacJiia, which 

 have compound racemose inflorescences with two flowers on each lateral 

 axis. 



Extreme inflorescence reduction accompanying vegetative reduction 

 is seen in annual and perennial herbs with solitary terminal flowers and 

 radical leaves — Cypripcdium, Tulipa. 



Inflorescences Resembling Flowers. Many greatly reduced inflores- 

 cences resemble flowers; some have passed as flowers in taxonomic 

 treatments. The flowerlike inflorescences of such families as the Com- 



Fig. 36. Reduced inflorescences. A, Euphorbia piilcherrima, median, longitudinal 

 section of one half an inflorescence, pistillate flower not shown, a, gland; b, stamen; 

 c, bracteole; d, articulation between pedicel and flower consisting of one stamen; 

 e, left secondary branch of dichasium; /, pedicel of flower; g, right secondary 

 branch of dichasium; h, two of three traces in stele of pistillate flower. B, Heliconia 

 bihai L., portion of inflorescence with side of single bract cut away to show, from 

 right to left, two unopened buds, flower in anthesis, and immature and mature 

 fruits on elongated pedicel. Each structure subtended by bract which subtends 

 a raceme of many flowers not shown. Water level indicated by broken lines. (A, 

 after Haber; B, after Skutch.) 



