14 HETEROSTYLED DIMORPHIC PLANTS. Chap. L 





CHAPTEE I. 



HETEROSTYLED DIMORPHIC PLANTS : PfilMULACRZB. 



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 

 Vitalliana. 



It has long been known to botanists that the com- 

 mon 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 fact, according to von 

 Mohl (' Bot. Zeitung,' 1863, p. 326), 

 was first observed by Persoon in 

 the year 1794. 



t In Johnson's Dictionary, 

 thrum is said to he the ends of 

 weavers' threads ; and I suppose 



that some weaver who cultivated 

 the polyanthus invented this 

 name, from being struck with 

 some degree of resemblance be- 

 tween the cluster of anthers in the 

 mouth of the corolla and the ends 

 of his threads. 



■-*' *ici 



