380 Dr Fulton on the Inflorescence, Floral Structure, and 



The flowers* are small, inconspicuous, and of an unusual 

 shape. The gamopetalous globose corolla is about the size 

 of a pea, and nearly horizontal in position. Its compara- 

 tively wide circular mouth is bounded by four lips — an 

 inferior, minute transverse and decurved ; two lateral, 

 vertical prominent and slightly everted ; and a bifid superior, 

 much the most ample and conspicuous, which projects 

 liorizontally as a roof above the matured reproductive 

 organs (Plate XTII. figs. 1-4). From tlie throat the 

 scale-like petaloid portion of the staminode projects 

 downwards and forwards, and may aid in protecting the 

 pollen from rain without increasing the conspicuousness of 

 the flower, or, as Trelease has suggested, in diminishing 

 the aperture of the corolla. f In colour the corolla is deep 

 brownish purple or purplish brown, most marked on the 

 upper part, and remarkably constant in tint. The nectary 

 appears to consist of the upper part of a pentagonal ring 

 encircling the base of the pistil. The lateral angles of the 

 thickened superior part (fig. 1, w) project into the base of 

 two sulci, situated between the adherent filament of the 

 staminode (s), which forms a mesial ridge, and the 



* The description always refers to S. aquatica, unless when otherwise 

 stated. 



+ MuUer suggests that this structure is of no importance and beyond the 

 influence of natural selection, but according to Dar\\-in rudimentary or aborted 

 organs are very liable to vary, and the following description of the variations 

 observed in about 1000 flowers examined by me will show that the staminode 

 is at all events not more variable than other parts of the flower : — (1) Tht 

 staminode varied only twice, both cases being on the same plant, and both 

 showing partial reversion to the poUeniferous condition. (2) Coherence of two 

 corollas in two calyces, with one ovary and pistil and eight stamens. (3) An 

 ordinary corolla, with two free styles and two partially coherent ovaries, and 

 four stamens. (4) The union of the two inner stamens in their entire length, 

 with the shortened style lying in a mesial groove on their upper surface, and 

 the stigma amidst the dehiscing pollen. (5) The external stamens completely 

 absent. (6) One of the inner stamens entirely petalised, and adhering to the 

 lower lip which was contorted. (7) One of the inner stamens partially petaloid, 

 and adherent to the lower lip ; a speck of pollen covered by a petaloid hood, 

 and a minute hollow petaloid spur distinctly yellowish at the tip. Besides 

 these, I found an unopened flower, twice the normal size, containing seven 

 minute saltatory looping mites, which had eaten the upper part of the 

 circumovarial disc (nectary) and part of the anthers. The sexual organs had 

 the position as in the bud ; the pistil small and stunted ; the stamens, 

 especially their filaments, enormously swollen. The pistil frequently varies in 

 length, sometimes just reaching the lower lip. The colour, except in the 

 monstrosity above-mentioned, I found constant. 



