1899.] NATURAL SCIENCES OF PHILADELPHIA. 95 



conceptiou of the consolidated parts of the flower. I take it we 

 are to look in this direction for the origin of the spur in the petals 

 of the violet, and in the fleshy appendages to the stamens, some- 

 times called nectariferous glands, which fill the spur spaces. Mr. 

 Darwin observes that he once saw Bomhm tervedris slit the spur of 

 Viola canina in search of the nectar these glands secrete, and it is 

 generally supposed they are nectariferous. But certainly in Viola 

 cuculhita they excrete nothing, as I infer, from not having been 

 sufficiently differentiated from their primary condition to be perfect 

 glands. Taking now, as we may again, the consolidated style, as 

 not merely the elongated extension of the carpels, but also of the 

 primary axis as well; and the thickened upper portion of the stvle 

 as a feeble effort to form another verticil of floral organs, the apex 

 of the primary shoot would be extremely likely to end in a com- 

 plete gland. If this view be correct, we have to look elsewhere for 

 the passageway to the ovules; unless indeed we conclude that it is 

 possible for nectariferous glands to serve as ducts for pollen tubes 

 in some instances, a circumstance I have sometimes suspected. 



VI. ISNARDIA PALUSTRIS ADDITIONAL NOTE ON ITS 



STIPULAR GLANDS.* 



I noted in 1886 that the usual description of Onagraceae — leaves 

 without stipules — was not strictly correct, as they were present in 

 the form of glands in Isnardia (Ludwigia) pa/ustris, the marsh 

 purslane. Dr. Asa Gray, to whose regular and friendly correspon- 

 dence through a number of years I am greatly indebted, wrote : 

 " You have certainly found something; but whether these glands 

 should be considered stipular or not, I am not prepared to say." 

 The matter had passed from my mind till recently, when the oppor- 

 tunity occurred to spend several hours in the midst of a large 

 quantity of the plant. 



At the base of the solitary axillary flower is a pair of minute 

 scales. The general resemblance of the gland and its connection 

 with the base of the petiole suggested the possibility that these 

 glands might also be bracts or scales that had come within the 

 connate power so potent in this species. This power is well exem- 

 plified in the structure of the flower. The stamens are opposite the 

 sepals, indicating that the petals have disappeared. Then Ave note 

 *Pron. Acad. Nat. Sci., 1886, p. 349. 



