Chap. IV, LTTHEUM SALICAEIA. 137 



CHAPTEE IV. 



Heteeosttled Tbimoephic Plants. 



Lythriim salicaria — Description of tbe three forms — Tlielr power and 

 complex manner of fertilising one another — Eighteen different 

 unions possible — ^Mid-styled form eminently feminine in nature — 

 Lythrum Grsefferi likewise trimorphio — L. tliymifolia dimorphic — 

 L. hyssopifolia homostyled — NessBa vertioillata trimorphio — Lager- 

 stroemia, nature doubtful — Oxalis, trimorphio species of — O. Valdi- 

 viana — O. Eegnelli, the illegitimate unions quite barren — 0. spe- 

 ciosa — 0. Bensitiva — Homostyled speciea of Oxalis— Pontedej-ia, 

 the one monocotyledonuus genus known to inclade heterostyled 

 species. 



In the previous chapters various heterostyled dimor- 

 phic plants have been desciibed, and now we come to 

 heterostyled trimorphio plants, or those which present 

 three forms. These have been observed in three 

 families, and consist of species of Lythrum and of the 

 allied genus Nessea, of Oxalis and Pontederia. In 

 their manner of fertilisation these plants offer a more 

 remarkable case than can be found in any other plant 

 or animal. 



Lythrvm salicaria. — The pistil in each form differs 

 from that in either of the other forms, and in each 

 there are two sets of stamens different in appearance 

 and function. But one set of stamens in each form 

 corresponds with a set in one of the other two forms. 

 Altogether this one species includes three females or 

 female organs and three sets of male organs, all as 

 distinct from one another as if they belonged to dif- 

 t'erent species; and if smaller functional differences 



