14 HETBEOSTYLED DIMORPHIC PLANTS. Chap. L 



CHAPTEE I. 



Heteeostyled Dimoephic Plants: PEuruLACEa!. 



Primula veris or the Cowslip — ^Differences in structure between the 

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

 imately united — ^P. elatior, vulgaris, Sinensis, auricula, &c. — Sum- 

 mary on the fertility of the heterostyled species of Primula — 

 Homostyled species of Primula — Hottonia palustris — ^Androsace 

 YitaUiana. 



It has long been known to botanists that the com- 

 mon Cowslip {Primula veris, Brit. Mora, 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 fact, according to von that some weaver who cultivated 



Mohl('Bot.Zeitung,'1863,p.326), the polyanthus invented this 



was first observed by Persoon in name, from being struct with 



the year 1794. some degree of resemblance be- 



f In Johnson' s Dictionary, tween the cluster of anthers in the 



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



weavers' threads ; and I suppose of his threads. 



