APRIL, 1904. PLANTS YUCATAN^: MILLSPAUGH & CHASE. 151 



LACTUCA L. Sp. PL, 795. 



Heads homogamous, flowers perfect, fertile, ligulate, ligules 5 

 toothed at the truncate apex. Involucre cylindrical or conoid, of 

 herbaceous bracts imbricated in several series, the outer shorter, 

 sometimes calyculate. Receptacle plane, naked. Achene com- 

 pressed, ribbed, tapering into a neck or beak, which is expanded at the 

 summit into a disk; pappus of copious soft, capillary, bristles. 

 Tall annual, biennial, or perennial herbs with milky juice. 



Lactuca intybacea Jacq. Ic. PI. Rar., i, t. 162. 



An erect, glabrous, branching herb with terete stem and branches 

 and alternate, runcinately pinnatifid leaves, clasping by a sagittate 

 base, lower leaves obovate, tapering at the base. Inflorescence an 

 elongated open panicle, branches ascending, strict, the heads distant, 

 solitary or few in a cluster, on short, bracteate pedicels. Heads 16 mm. 

 high, 10-11 mm. broad, 12-15 

 flowered. Involucre cylindrical, 

 outer bracts short, calyculate, 

 broadly ovate, acute, with a white 

 hyaline margin, inner in 2 series, 

 equal, oblong, obtuse, white hya- 

 line margined. Corolla yellow, 

 ligule oblong. Achene black, 

 .8x3.8 mm.; fusiform, tapering 

 into a short neck; in section 

 rhomboid-oval; impressed stri- 

 ate, interspaces tuberculate-ru- 

 gose; pappus bristles white or 

 cream color, 7 mm. long. 



Hab. Herb, 3 feet high, 

 common in old corn-fields at 

 Silam, April, Gaunter 877 (Stepha- 

 nomeria runcinata Field Col. Mus. Bot. i '.325), Silam 2012; small but 

 fully developed specimens 15-20 cm. high, simple stemmed, from 

 grassland near Progreso, Millspaugh PL Utowance. f?of, taller branch- 

 ing plants from the same locality 1706, 1709; Sayi, March 4, 1903, 

 Ccec. et Ed. Seler 3897. 



[LACTUCA sp.? 



Not in flower, "common in waste places near Merida, Valdez 48 

 (Erechtites sp. Field Col. Mus. Bot. 1:323).] 



