T. Holm — North American Species of Stella ria. 317 



So far as concerns the perennial North American species of 

 Stellaria s. s. (not including Malachium and Cherleria) the 

 primary root is only of short duration, but becomes replaced 

 by secondary roots developing from the basal nodes of the 

 aerial stem or from the rhizome. Very characteristic of sev- 

 eral of these species is the ability of the stems above ground 

 to remain active for more than one season, beside that some of 

 these are, moreover, provided with true rhizomes ; in one 

 species we find the shoots to be differentiated as floral and 

 vegetative, the former being merely annual, while the latter 

 may persist for about two seasons. Finally in another species 

 we notice a highly developed rhizome with fleshy, swollen 

 internodes, resembling long tubers. We might thus distinguish 

 between these types so far as concerns the vegetative repro- 

 duction, viz : 



A, without rhizome, but with persisting aerial stolons. 



B, with rhizome, and with persisting aerial stems. 



C, with rhizome, but without persisting aerial stems. 



Of these the first type is represented by Stellaria pubera 

 Michx. and may be described as follows : 



Stellaria pubera Michx. 



The plant is generally in full bloom in April or in the earlier 

 part of May ; the floral shoots are quite numerous, spreading, 

 and leafy to the top. The inflorescence is a regular, very rich- 

 flowered cyme. About the middle of May, or even earlier, 

 while the plant is still blooming, a few vegetative shoots com- 

 mence to develop (Y in fig. 1). The leaves of these shoots 

 are always larger than those of the floral, but otherwise in 

 regard to pubescence and outline the foliage is the same.* It 

 is now interesting to see, that while the floral shoots die down 

 to the ground as soon as the fruits have matured, the vegetative 

 shoots not only remain active, but they continue their growth 

 for several months with the leaves fresh and green. Some- 

 times a few-flowered inflorescence develops at the apex of 

 these shoots, but it seems to be the most frequent case that 

 they stay as purely vegetative. Although these flowers become 

 developed much later than the others (those of the normal, 

 floral shoots), they are, nevertheless, perfect, and of the same 

 size or even larger than the earlier ones. If we examine the 

 plant in the month of August or early in September, we find 

 the vegetative shoots still alive, but closely appressed to the 



* As stated in the Synoptical Flora, p. 236, "the stems are pubescent in 

 lines" mostly so, but not always ; in the vicinity of Washington, D. C, it is 

 not uncommon to find, individuals as the one figured (fig. 1) in which the 

 pubescence is not in lines but equally distributed all over the stems and 

 branches of the inflorescence. 



Am. Jour. Sci. — Fourth Series, Vol. XXV, No. 148.— April, 1908. 



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