RANALES 419 



uniseriate, and as biseriate with corolla reduced. The trimerous 

 androecium is, morphologically, perhaps the most important part of the 

 flower. There are four, sometimes five, whorls (Fig. 47). The outer two 

 are introrse; the third, extrorse, with associated nectaries; the innermost 

 whorl or whorls are represented by nectaries or lanceolate staminodia 

 (Fig. 45). The nectaries, one on each side of the filament, are usually 

 stalked, but sometimes sessile. The stalked form with enlarged tip is 

 borne on the receptacle at or near the base of the filament, often united 

 with the filament just above the base; secretion is from the enlarged 

 terminal part. The sessile form is borne on the filament at various levels. 



There has been disagreement about the morphology of these nectaries. 

 The general opinion, based on comparative and anatomical studies, is 

 that the nectaries are modified stamens, but they have been called mere 

 "glandular protuberances." The interpretation of the nectaries as mor- 

 phologically stamens is an important element in phylogenetic considera- 

 tions. Evidence of several kinds supports this interpretation of nectaries 

 derived from stamens. The lauraceous stamen has four sporangia in 

 pairs, one above the other, with valvular dehiscence. (Some genera, 

 such as Lindera, have two functional sporangia, two others abortive.) 

 Stamenlike characters that persist in the stalked nectaries are the fila- 

 mentlike stalk and the more or less anther-shaped tip (Persea); the 

 occasional formation of pollen by some nectaries; in some genera, at- 

 tachment of nectaries on the receptacle free from the stamen; the re- 

 semblance of early primordial stages of the nectary to anther primordia; 

 in pistillate flowers, the similarity of the nectaries to the vestigial 

 stamens. Vascular anatomy strongly supports the staminal nature of 

 these nectaries. Though their vascular structure is complex within the 

 secretory region — with many minute strands, as always in nectariferous 

 tissues — the origin and course of the vascular supply is the same as that 

 of the stamens. Where the nectary stalk is free, or nearly so, at tlie 

 base, one trace, independent in the torus, passes into and through tlie 

 stalk to the enlarged tip, as in a stamen — Lindera; where the nectaries 

 are adnate to the stalk, the filament has three bundles (in some genera, 

 five — Persea), and the outer, lateral bundles arise independently in the 

 receptacle by the division of a single bundle of the floral stele and 

 pass independently through the filament to die glands — Umhellularia 

 (Fig. 45). Less commonly, the three bundles remain united in origin 

 and part way through the filament. 



The location of the nectaries, individually beside the stamens and 

 in groups with a common vascular supply, supports the interpretation 

 of the androecium of this family as fasciculate; each stamen, with its 

 associated nectaries, represents a fascicle of three stamens, probably 

 five in those genera where the stamen base has five bundles. "Stamen 



