1-fIowered; calyx campanulate, regular; corolla scarcely longer than calyx; petals 

 oblong, acute, sparsely papillate within, white or pink, nearly regular; stamens 4; 

 style short, 0.2-0.4 mm. long; stigma obscurely 2-lobed; capsule ovoid, about 

 3 mm. long, 2-celled, many-seeded, ridged, reticulate; seeds much longer than 

 wide. 



Along margins of pools, on stream banks, in irrigation ditches, in mud and 

 shallow water of ponds and lakes, in N.M. (widespread) and Ariz. (Coconino 

 and Pinal cos.), June-Sept.; almost throughout N.A. except s.e. U. S.; Euras. 



3. Mecardonia R. & P. 



Erect or diffuse much-branched glabrous herbs from a perennial root, often 

 becoming black upon drying; stems 4-angled; leaves opposite, narrowed to a 

 sessile base, toothed, glandular-punctate; flowers axillary in leaflike bracts; bract- 

 lets 2, at the base of the slender pedicel and much shorter than the bracts; sepals 

 5, unequal, the outer ones much wider than the inner ones; corolla bilabiate with 

 the lobes shorter than the tube, the posterior lip more or less united and pubes- 

 cent within at base; stigmas liplike; capsule cylindric to ovoid, acute, glabrous, 

 septicidal, the valves only slightly loculicidal at apex; seeds numerous, cylindric, 

 reticulate, wingless. 



About a dozen species in warmer parts of America. 



1. Corolla yellow, its upper bearded lobes essentially united or forming only a 

 slightly notched lamina; 3 outer sepals broadly ovate to ovate- 

 elliptic, more than 3 times as wide as the 2 inner sepals; leaves 

 typically ovate or oval, abruptly cuneate at base, less than 25 mm. 

 long; plant procumbent or ascending 1. M. vandellioides. 



1. Corolla white, often with purplish stripes, its upper bearded lobes typically 

 separated at least one third their length; 3 outer sepals lanceolate, 

 rarely more than 2 times as wide as the 2 inner sepals; leaves 

 typically oblanceolate, tapering to the narrow base, more than 3 

 cm. long; plant erect or diffusely branched 2. M. acuminata. 



1. Mecardonia vandellioides (H.B.K.) Penn. Fig. 686. 



Plant very variable, glabrous throughout; stems procumbent to erect-ascending, 

 often branched and widely spreading from the base, to about 4 dm. long; leaves 

 opposite, sessile, ovate to oval or obovate to obovate-oblong, obtuse to subacute, 

 more or less serrate or serrulate above the middle, 1-2.5 cm. long; pedicels 

 axillary, solitary, usually noticeably exceeding the subtending leaf and the 2 

 small basal bracteoles; calyx 5-parted, the 2 interior lobes linear, the 3 outer 

 lobes broadly ovate to ovate-elliptic, acutish, sometimes serrulate above the 

 middle; corolla 6-12 mm. long, always longer than the calyx, bilabiate, yellow 

 with longitudinal dark veins on the essentially united upper pair of lobes; capsule 

 ellipsoid, about as long as or shorter than the calyx. M. procumhens (Mill.) Small, 

 M. pedunciilaris (Benth.) Small, M. viridis Small, M. montevidensis (Spreng.) 

 Penn., Pagesia peduncidaris (Benth.) Penn., P. vandellioides (H.B.K.) Penn. 



In mud and water of ditches, lagoons, ponds and streams, and in moist soils of 

 depressions, mostly in cen., s., and w. Tex., and Ariz. (Cochise, Santa Cruz and 

 Pima COS.), Mar.-Nov.; from Fla. to Tex., Ariz, and Mex., s. to s. S.A. 



2. Mecardonia acuminata (Walt.) Small. Fig. 686. 



Stems from a subligneous crown, erect or ascending, glabrous, simple to 

 branched, to about 7 dm. high; leaves oblanceolate to oblong-lanceolate, mostly 

 narrowly obtuse, tapering below to a narrowly cuneate base, firm, serrate above 

 the middle, mostly 2-4 cm. long; pedicels filiform, equaling or surpassing the 

 subtending leaves and 2 small basal bractlets; outer 3 sepals oblong-lanceolate, 

 broader than the lanceolate inner 2 sepals; corolla white, often tinged or lined 

 with purple, 7-10 mm. long, bearded within at the base of the upper obviously 



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