CLAYTONIA GRONOV.— THEO. HOLM. 29 



III. THE MORPHOLOGICAL STRUCTURE OF THE SHOOT. 



The primary shoot represents a monopodium in nearly all the species. The main axi.s hears 

 in these only leaves, which are always green and developed as proper leaves; it is from the axils 

 of these that the flower-hearing- stems develop in the first year, when the species is an annual, but 

 much later if it is a perennial. A rhizome is often developed and in a very different manner, 

 which depends not only upon the structure of the rhizome itself, but also upon the structure of 

 the root system. The species of Claytonia exhibit altogether a striking diversity as far as 

 concerns their mode of growth, and it is strange to see how differently certain species behave in 

 this respect, although they are otherwise to be considered as near allies. A classification of the 

 species from a biological view point must, therefore, result in the separation of related types, at 

 least in some instances. 



These biological types may be arranged as follows: 



I. ANNUALS. 



A. — The shoot ia terminated by an inflorescence (C. linearis Dougl., C. diffusa Nutt., C. dichotoma Nutt.). 

 B. — The apex of the shoot is vegetative, represented by a rosette of leaves ( C. Sibirica L., C. arenicola Hend., 

 C. perfoliata Dow., (.'. parrijloni Docgl., ('. ijypsophil.oides Fisch. etMsy., C. spathulata Dougl. ). 



2. PERENNIALS. 



C. — As B, but with a fleshy, horizontal rhizome and filiform secondary roots (C. asarifolia Boko. ). 



D. — As C, but the rhizome is very short and slender, and bulblets are developed in the axils of the stem leaves. 

 I ( '. parvifolia Moo). 



E. — Monopodial, as those above (from B to D inclusive), but the rhizome is erect and short with a very large 

 root, the primary (('. Yirginlca L., C. Caroliniana Michx., C. lanceolata Pursh, C. rnegarrhiza Parry, ' '. arctica 

 Adams). 



F. — Monopodial, with stolons above ground and slender root ( C. sarmentosa Mey. ). 



< i. — Not monopodial, with filiform roots and stolons underground, i iften terminated by bulblets. ( ( '. Chamissonis 

 Esch.). 



Seven well-marked biological types are thus characteristic of these eighteen species of 

 Claytonia. Let us examine these a little further. 



Among the annuals, ('. linearis Dougl., C. diffusa Nutt., and ('. dichotoma Nutt., it 

 appears as if the primary axis becomes continued into an inflorescence. We use the expression 

 "appears" since the material which we have examined was not quite sufficient or satisfactory for 

 this purpose; moreover, only dried specimens were at our disposal. The larger specimens were 

 profusely branched in the first of these species, and the true ramification could not be made out 

 beyond that the leaves were all alternate and that there was no trace of any basal rosette, so 

 very distinct and readily observable in all the other annuals of the section B. In some small 

 specimens the cotyledons were still preserved, and they were linear and above ground. Only 

 two inflorescences were developed in these specimens, and from the same height, and either were 

 both axillary and pertaining to the cotyledons, or the one was axillary and the other one terminal. 

 The latter explanation seems to be the more probable, inasmuch as there was no evidence of any 

 rudimentary terminal bud. However, a renewed examination of fresh material may prove the 

 opposite. 



All the other annuals which we have examined possessed a rosette of leaves from the 

 axils of which the flower-bearing stems had developed. The primary root is long and slender. 

 Claytonia Sibirica L. belongs to this category, but it appears as if this species also occurs as 

 perennial, judging from a note in Gray's paper cited above. This author states that it is "a pure 

 annual when it grows in exsiccated soil, but when better nourished it is more enduring and bears 

 offsets on stout stolons from the crown, and so, in the absence of much winter's cold, its life is 

 continued and extended from year to year." We have not been able to secure any material that 

 showed such modification, but it is interesting to know that a perennial form does exist of this 

 species, and that it is stoloniferous; in certain other genera and of remote orders similar per- 



