PEDUNCLE • DICTIONARY ONE.COM • Definition of Peduncle

... or elliptic leaves, which are glabrous and have long petioles. The terrestrial plants are erect, nearly simple, more or less hispid throughout, with lanceolate leaves and short petioles, often nearly sessile. The aquatic form flowers regularly, producing its peduncle at right angles from the floating stems, but the terrestrial specimens are ordinarily seen without flower-spikes, which are but rarely met with, at least as far as my own experience goes. Intermediate [434] forms are very rare, perhaps wholly wanting, though in swamps ...

— Species and Varieties, Their Origin by Mutation • Hugo DeVries