PLATE 33. 



BLUE LETTUCE, Laduca pulchdla. DC. 



Other English names : Showy Lettuce, Large-flowered Blue Lettuce. 

 Other Latin names: Mulgedium jjulchellum, Nutt.; Mulgedium acu- 

 minatum, DC; Sonchus 'pulclielliis, Pursh. 



Native. Perennial, deep-rooted. Stems 2 to 3 feet, leafy below. Whole 

 plant smooth and glaucous, filled with milky juice. Leaves very variable, 

 anear-lanceolate or oblong; entire, simply or runcinately dentate, or pin- 

 natifid ; stem leaves less divided and sessile. Flower heads nearly 1 inch 

 across, pale blue, rather few, on scaly peduncles in a narrow panicle. Seeds 

 [Plate 56, fig. 68 — natural size and enlarged 4 times] about i\- of an 

 inch, one-quarter of which is a short thick beak ; tip of beak expanded 

 into a short cup-shaped disk ; slaty gray when ripe, red when immature ; 

 club-shaped, flattened, with thick rib-like margins and with narrower ridgea 

 down each face; in some seeds one or more of these ridges much thickened, 

 whole surface dull and rough ; pappus pure white and silky. 



Time of Flowenng : June, July; seed ripe by end of July. 

 Propagation : By seeds and by fleshy running rootstocks. 



Occurrence: Prairie Provinces and British Columbia. In moist or 

 sandy soil, particularly where there is some alkali. 



Injury: A deep-rooted and persistent perennial weed. 

 Remedy : Early summer-fallowing. 



The Prickly Lettuce, Lactuca Scariola, L. (Noxious : Man.) This 

 coarse-growing prickly-leaved annual has spread rapidly through Canada 

 during the past four or five years. Although, as a rule, it occurs most com- 

 monly in waste places, the seeds [Plate 56, fig. 67 — natural size and enlarged 

 4 times] are frequently found among crop seeds. These are dark gray, sim- 

 ilar to those of the black-seeded varieties of the garden lettuce, usually a 

 little smaller, and like them are broadly lance-shaped and somewhat curved, 

 flattened, margined and bearing 5 to 7 narrow ridges down each face; whole 

 surface roughened, with very short white bristles on the ridges near the apex ; 

 beak as long as the seed, very slender and often twi.sted ; pappus white. In 

 the Eastern parts of Canada, where the Prickly Lettuce is now common in 

 many places, plants average 3 to 5 feet in height: but in the Okanagan val- 

 ley of Britisli Columbia plants were found some years ago which were 8 feet 

 high. The leaves are oblong-lanceolate, spiny margined and prickly on the 

 midrib beneath, more or less pinnately divided, .sessile with ear-like lobes at 

 the base. The flower heads are pale yellow, less than A inch across and only 

 a few open at a time on the large wide-spreading panicle. 



The leaves of the stem are twisted at the clasping base so as to stand 

 vertically witli the edge to the sun, instead of horizontally, as in the case 

 of the leaves of most plants. This peculiarity has given rise to a common 

 name of this lettuce, the Compass Weed. 



It is claimed by some botanists that the Prickly Lettuce, which is found 

 in waste places in Canada, is tlie European Lactuca virosa, L. ; but the two 

 are difficult to separate with certainty. For the meantime it seems prefer- 

 able to use the best-known name L. Scariola. 



(.5) 65 



