A Peculiar Specimen of Arctium 



137 



iate and lobed, divisions tipped with small bristles; lamina 

 almost entirely absent on one side of the mid-rib in some leaves, 

 and ranging from this to an entire absence, merely petiole and 

 mid-rib being present. Some petioles were branched, each 

 division bearing a leaf blade. Normally in Arctium there is a 

 petiole at the base of each flower stalk, but in this plant two to 

 four small ones seemed to be present in places. These super- 

 numerary petioles bore no leaf blades. Sections of the stem 

 and petioles showed a microscopical structure very similar to 

 that found in corresponding parts of Arctium minus. 



The inflorescence was irregular, heads numerous, mostly 

 small, rudimentary, and apparently sterile; two were about fif- 

 teen millimeters wide and had purple flowers; heads mostly 

 sessile or nearly so, on or near the ends of the branches; involucre 

 subglobose, its bracts rigid, tipped with spreading or erect 

 hooked bristles. The whole plant had the characteristic odor, 

 texture, and general appearance of Arctium. 



In trying to account for this peculiar plant form some 

 interesting questions arise. One may think at once that it is 

 an immigrant since it was found along the railroad, but an 

 examination of current manuals and systematic treatises failed 

 to reveal much concerning the occurrence of such a form. In 

 some of the older editions of Gray's Manual, the statement is 

 made that Arctium Lappa var. minus rarely has laciniate leaves. 

 In the new edition this characterization is omitted. In Small's 

 Flora of the Southeastern United States, the statement is made 

 in the characterization of the genus Arctium that the leaves are 

 rarely laciniate or pinnatifid. This form of the plant being so 

 rare there is more likelihood that it originated locally than that 

 it was imported. 



It is an interesting question as to how much the environ- 

 ment had to do with the production of such a type. It was 

 growing under rather hard conditions, the soil being the dry, 

 gravelly clay of a railroad grade; it was not shaded. The laci- 

 niate nature was not a result of the plant's being mowed often 

 for it appeared in the first year's growth, while in the rosette 

 stage. 



Since the plant had leaves that resembled somewhat the 

 leaves of certain species of Carduus, being lanceolate, laciniate 



