STUDIES IN PORTULACACE.E. 



BY KATHARINE BRANDEGEE. 



Many of the plants of this order are difficult of investi- 

 gation in herbarium specimens. The texture of the co- 

 rolla is often so delicate that it can only be unfolded with 

 considerable trouble. The frequently minute crustaceous 

 seeds are equally troublesome. The slow process of 

 germination can only be resorted to in a few species at 

 once, and in dissection they require more than usual 

 care. That they have been neglected is evidenced by Dr. 

 Gray's remark concerning the accumbent cotyledons of 

 Lewisia rediviva, " So far as we know, it is not so in any 

 other Portulacaceous plant, not even in L. br achy calyx.'"* 

 This supposed exceptional position of the embryo is the 

 character relied upon by Mr. Howell in separating the 

 second species of Lewisia, and with it aggregating all 

 the forms of Claytonia and Calandrinia having a circum- 

 scissle capsule, under the generic name of Oreobroma.f 

 The discovery of some undescribed forms in the herba- 

 rium of the California Academy of Sciences having led 

 to the investigation of the embryos of all the accessible^ 

 genera, the results reached were somewhat unexpected, 

 but sufficiently show that the position of the cotyledons is 

 of no generic significance, and in those forms in which 

 they are oblique (it is often impossible to be sure whether 

 they are obliquely incumbent or accumbent) perhaps not 

 even specific. 



** Proc. Am. Acad., xxii, 276. 

 tErythea, i, 31. 



t No specimens seen of Talinopsis, Pleuropetalum, Grahamia, Auacam- 

 peros. 



2d See., Vol. IV. March 2C, 1894. 



