ALISMACEAE 
171 
minal segment large and triangular, lower petioled, upper sessile.—Old 
fields and waste places; nat. from Eur. 
2. S. asper L. Prickly Sow-Thistle. Similar to no. 1; leaves 
sometimes undivided.—Old fields and waste places; nat. from Eur. 
41. LACTUCA L. Lettuce 
Tall leafy-stemmed annuals or biennials with panicled heads of yellow 
or purple flowers. Leaves alternate. Involucral bracts imbricated in 2 
or more series of unequal lengths. Rays 5-toothed. Pappus of soft white 
capillary hairs which fall separately. (Ancient Latin, from lac, milk, 
referring to the milky juice.) 
1. L. scariola L. Prickly Lettuce. Stems paniculately branched 
above, 5.7 to 14 dm. high; leaves oblong or oblong-lanceolate, pinnatifid, 
sessile or clasping, with a row of soft prickles on the lower side of the 
midrib: heads numerous; rays cream-vellow.—Introduced from Europe; 
roadsides, waste places and grain fields. Cows are fond of the green 
herbage. 
2. L. sativa L. Garden Lettuce. Similar to no. 1 but with unarmed 
midrib.—Cult, from Eur. as a salad plant for man. 
42. AGOSERIS Raf. 
Herbs, the stems naked and scape-like, bearing single large heads. 
Leaves in a basal tuft, elongated. Flowers yellow. Involucre cam- 
panulate, its bracts imbricated. Achenes 10-ribbed, prolonged into a fili¬ 
form beak. Pappus-bristles fine, copious. (Greek agos, chief, and seris, 
lettuce.) 
1. A. heterophylla (Nutt.) Greene. Annual; stems slender, 7.2 to 
28.8 cm. high; herbage villous-pubescent; leaves linear to oblong, entire, 
denticulate or sinuate pinnatifid; involucral bracts lanceolate-acuminate; 
achenes 2 to 4 mm. long; beak 4 to 8 mm. long.—S. Cal.; Sierra Nevada, 
North Coast Ranges. 
2. A. plebeia Greene. Perennial; stems stout, 3.8 to 4.8 dm. high; 
herbage hirsute-pubescent to glabrate; leaves lanceolate or spatulate, en¬ 
tire, dentate, laciniate or lobed ; achenes 5 to 6 mm. long, the beak 14 to 
20 mm. long.—San Francisco Bay region to S. Cal. 
Class II.—MONOCOTYLEDONS 
ALISMACEAE. WATER PLANTAIN FAMILY 
Marsh or aquatic herbs with basal leaves, scape-like flower stems and 
perfect or unisexual flowers. Perianth of 3 outer herbaceous persistent 
sepals and 3 inner white delicate deciduous petals. Stamens 6 to many or 
numerous. Ovaries numerous, distinct, 1-celled, 1-ovuled, becoming 
achenes in fruit. Endosperm none; embryo strongly recurved or folded. 
—Species about 50, temperate and tropic zones. 
Achenes verticillate in a single whorl; stamens 6. 1. Alisma. 
Achenes crowded on a globose receptacle; stamens numerous. 2, Sagittaria. 
