14 HETEEOSTYLED DIMOEPHIG PLANTS. Chap. I. 



CHAPTEE I. 



IIeteeosttled Dimorphic Plants: PBnrDLACEai. 



Piimnla veris or tlie Cowslip — Differences in structure between tho 

 two forms — Their degrees of fertility when legitimately and ille- 

 gitimately united — P. elatior, vulgaris, Sinensis, auricula, &o. — 

 Summary on the fertility of the heterostyled species of Primula — 

 Homostyled species of Primula — Hottonia palustria — Androsace 

 Vitalliana. 



It has long been known to botanists that the common 

 Cowslip (Primula veris, Brit. Flora, var. officinalis, 

 Lin.) exists under 4;wo forms, about equally numerous, 

 which obviously differ from each other in the length 

 of their pistils and stamens.* This difference has 

 hitherto been looked at as a case of mere varia- 

 bility, but this view, as we shall presently see, is far 

 from the true one. Florists who cultivate the Polyan- 

 thus and Auricula have long been aware of the two 

 kinds of flowers, and they call the plants which dis- 

 play the globular stigma at the mouth of the corolla, 

 " pin-headed " or " pin-eyed," and those which dis.play 

 the anthers, " thrum-eyed." t I will designate the two 

 forms as the long-styled and short-styled. 



The pistil in the long-styled form is almost exactly 

 twice as long as that of the short-styled. The stigma 



• This fact, according to von that some .weaver who cultivated 



Mohl ('liot. Zeitung,' ] 863, p. 326) the polyanthus invented this name, 



was first observed by Persoon in from being struck with some degree 



the year 1794. of resemblance between the cluster 



t In Johnson's Dictionary, of anthers in the mouth of the 



thrum is said to be the ends of corolla and the ends of his 



weavers' threads; and I suppose thieads. 



