72 



POLYSEPALY, ETC. 



[CH. 



The next point of importance in regard to the floral 

 envelopes concerns the freedom or union of the sepals 

 or petals. In the Buttercups, Wallflower, Chickweed, 

 Geraniums, &c., direct observation shows that each sepal 

 and each petal originates as a free organ, and remains 

 separate throughout its life, and the calyx and corolla are 

 'polysepalous and polypetalous respectively, as we have 

 seen ; whereas in the Pinks, Catchfly, Gorse, Whin, La- 

 burnum, Robinia, &c., the calyx is gamosepalous and the 

 corolla polypetalous, because, as the young sepals de- 

 velope, their basal parts all grow up as a common ring 

 of undifferentiated tissue. In the Heaths, Bittersweet, 

 &c., again the calyx is gamosepalous and the corolla 

 gamopetalous. 



The following afford examples of a gamosepalous 

 calyx : 



Ulex Genista Robinia 



Bittersweet Tea-tree SarotJiamnus 



Laburnum Privet Lilac. 



This condition merges into one where the bases of the 

 sepals are merged into a calyx-tube, as in 



RJiamnus Rubus Almond 



CraUegus Pyrus Elceagnus 



Primus Rosa Ribes 



Cotoneaster Daplme, 



