( 2S6 ) 

 Observations suggested hy the 'preceding Pa'per. 



Bj William Trelease. 



While engaged in a systematic study of North American Gera- 

 niacecB last winter, I was obliged to give considerable time to the 

 yellow-flowered Oxa/is that has commonly gone under the name 

 of O. stricta, now reduced to varietal rank under the name of O. 

 corniculata ; and I had not gone far before I perceived that the sub- 

 ject in hand was one of unusual difficulty. Caulescent forms of 

 this genus, with trifoliolate leaves and (mostly small) yellow flow- 

 ers, are found over the larger part of the globe ; and as those of 

 dirterent countries differ considerably in size and habit, they have 

 been described under a variety of names. Even the American 

 forms have no less than ten names. But a comparison of the 

 plants from several countries shows, that, while they may be 

 quite different from other species associated with them, they can- 

 not in general be characterized with sufficient precision to justify 

 their separation from each other as distinct species, without adopt- 

 ing for them a scale of specific characters much more trivial than 

 those employed for other sections of the genus. For this reason 

 the disposition of botanists most familiar with plants of large 

 range, is to unite them under the Linnaean O. corniculata^ retaining 

 varietal names for the most distinct forms. 



A preliminary comparison of our North American plants led 

 very readily to the same conclusion. Utilizing the customary 

 characters derived from habit of growth, pubescence, presence or 

 absence of stipules, etc., our plants of this section go together 

 very well, although the stout caudex of the southwestern O. 

 Wrightii may properly be held, in so far as our ffora is concerned, 

 as of specific value ; yet in a monograph of the entire genus I 

 doubt if it would be so considered by many botanists whose opin- 

 ion is authoritative. Excluding this, our forms of O. coniictilata 

 are : 0. corniculata^ proper, which varies much, and is the first to 

 bloom about St. Louis, where, as it first comes up, it is recog- 

 nized at a glance from its white appressed pubescence, rather 

 large bright yellow ffowers, and squarrose stipules — at length be- 

 coming remote as the internodes of the stem elongate. In dry 



