14 HETEEOSTYLED DIMOEPHIC PLANTS. Chap. L 



CHAPTER I. 



HeTEROSTTLED DiMOBPHIO PlAIJTS; TsaiXShACBJE. 



Primula veris or the Cowslip — Diiferences in structure between th» 

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

 gitimately united — ^P. elatior, vulgaris, Sinensis, auricula, &c. — 

 Summary on the fertility of the heterostyled species of Primula — 

 Homostyled species of Primula — Hottonia palustris — ^Androsace 

 VitaUiana, 



It has long been known to botanists that the common 

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

 Lin,) exists under two 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 display 

 the anthers, " thrum-eyed." f 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 fiw-t, according to von that some weaver who cultivated 



Mohl ('Bot. Zeitnng,' 1863, 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 threads. 



