2. Verbena L. Vervain 



Herbs; stems and branches procumbent, ascending or erect, glabrous or vari- 

 ously pubescent; leaves mostly opposite, dentate (very rarely entire) or variously 

 lobed, incised or pinnatifid; inflorescence spicate, terminal, usually densely many- 

 flowered, often flat-topped and pseudo-umbellate, sometimes greatly elongate 

 with scattered flowers, very rarely also axillary; flowers small or medium-sized, 

 each solitary in the axil of a usually narrow bractlet; calyx usually tubular, 5- 

 angled, 5-ribbed, unequally 5-toothed, not at all or but slightly changed in fruit; 

 corolla salver- or funnelform, its tube straight or curved, often slightly ampliate 

 at the apex, the limb flat, weakly 2-lipped, lobes 5, usually rather elongate, ob- 

 tuse or rounded to emarginate at apex; stamens 4, didynamous, inserted in the 

 upper half of the corolla tube, mostly included; anthers ovate, with parallel or 

 slightly divergent thecae, the connective unappendaged or glandular-appendaged; 

 style single, usually short, shortly 2-lobed, the posterior lobe smooth, the anterior 

 lobe broader, papillose and stigmatic; ovary 2-carpellary, 4-lobed, completely 4- 

 celled, 4-ovulate; fruit mostly enclosed by the mature calyx, schizocarpous, readily 

 separating at maturity into four 1 -seeded linear cocci. 



A complex genus of about 206 species, 122 named varieties and forms, and 

 49 named hybrids, mostly of temperate and tropical America; 2 or 3 species native 

 to the Mediterranean region and introduced elsewhere in the Old World; many 

 are widely cultivated and tend to escape. 



1. Heads or spikes crowded and short (at least during anthesis), not at any time 

 greatly elongate or open, generally disposed in compound cymes 

 (2) 



1. Spikes slender and open or compact at anthesis, greatly elongate in fruit, 



solitary or in simple cymes or panicles (3) 



2(1). Leaves semiamplexicaul and subcordate at the base 1. V. bonariensis. 



2. Leaves tapering into a' cuneate—attenuate subsessile or petiolar base 



2. V. brasiliensis. 



3(1). Spikes panicled at the apices of the stem and branches, subtended chiefly 

 by inconspicuous bracts; floral bractlets not prominent (4) 



3. Spikes solitary or in 3's at the apices of stem and branches or panicled and 



subtended by leafy bracts at the base; floral bractlets often con- 

 spicuous (9) 



4(3). Spikes very slender, elongate and graceful, usually with remote fruits (5) 



4. Spikes thicker and densely flowered, usually with contiguous fruits (8) 



5(4). Leaves very scabrous above; fruiting calyx spreading; calyx lobes con- 

 nivent; stigmatic surface subtended by 2 sterile style lobes (6) 



5. Leaves not pronouncedly scabrous above; fruiting calyx ascending; calyx lobes 



not connivent; stigmatic surface subtended by 1 sterile style lobe (7) 



6(5). Leaf blades ovate, to 5 cm. wide 3. V. scabra. 



6. Leaf blades narrowly elliptic to elliptic-lanceolate, to 2 cm. wide 



3. V. scabra f. angustifolia. 



7(5). Lower leaf surface glabrous or scattered long-pilose 4. V. urticifolia. 



1. Lower leaf surface uniformly and densely short-pubescent 



4. V. urticifolia var. leiocarpa. 



8(4). Leaf blades membranous, not conspicuously scabrous above, mostly glab- 

 rous or inconspicuously strigillose beneath 5. V. hastata. 



8. Leaf blades rigid, harshly scabrous above, often conspicuously pubescent be- 

 neath 5. V. hastata var. scabra. 



1396 



