444 Annals of the Carnegie Museum. 



Lactuca canadensis var. spimdosa var. nov. 



The form of wild lettuce which becomes so abundant in neglected 

 upland meadows in the Pittsburgh district appears not to be the same 

 as that which has long passed as Lactuca canadensis. As Linnaeus 

 characterized it, at least under the synonymy which he quoted (Species 

 Plantarum II, p. 796), Lactuca canadensis does not have spinulose 

 midribs, and in the keys and descriptions in the current manuals of 

 today it is usually characterized as distinctly glabrous and with beak 

 and achene of equal length. Gray, however (Synoptical Flora of 

 North America, 1886, p. 442), says "Midrib naked or rarely some 

 sparse bristles," and he there mentions also that the achene is " rather 

 longer than the beak,'' a characteristic of the plant as it occurs in 

 western Pennsylvania, but hardly in accordance with the treatment 

 given it in most of the current manuals. 



A typical specimen collected by the writer. July 21, 1918, in a 

 neglected hill-top meadow about one mile north of Glenshaw. Alle- 

 gheny County, Pennsylvania, altitude about thirteen hundred and 

 twenty feet above the sea, may be described as the type of the new 

 variety: 



Lactuca canadensis variety spinulosa var. nov. 



Stem erect, rigid, but moderately slender, smooth, tinged and 

 speckled with purple, rather densely leafy, abundantly branching 

 above into an open panicle of broadly oblong outline. Leaves about 

 10-15 cm. long, about two-fifths as wide, pale beneath, sagittate- 

 clasping, the lower narrowed into winged petioles, the upper sessile, 

 all more or less runcinately pinnatifid and somewhat spinose-dentate, 

 the terminal lobe elongated, most of the lobes broadening above the 

 base and acuminate, the lower side of the midrib, especially in the 

 basal leaves, furnished with rather weak spinose hairs. Heads nu- 

 merous, the involucre 10-12 mm. high, the lower short bracts pur- 

 plish, the inner long ones scarious-margined ; the flowers about 14-17 

 in number, light yellow; the achenes about 3 mm. long, oblong-oval, 

 brown to blackish, transversely rugulose, thin, the margin about two- 

 thirds as wide as the body of the achene, the beak slender and about 

 2 mm. long, the pappus soft and shining white, about 6 mm. long. 



In richer and moister soil the plant may become at least twice as 



