APOCYNACEAE (DOGBANE FAMILY) 661 



cm. broad, thickisli ; petioles filiform ; lobes of the white corolla broadly oval, 

 about 1 cm, long, naked, except the crest-like yellowish gland at the base, twice 

 the length of the lanceolate calyx-lobes ; style none ; seeds smooth and even. 

 (Limnanthemum Griseb.) — Shallow^ water, N. S. to Fla., and locally westw. 

 July-Sept. 



2. N. aquaticum (Walt.) Fernald. Leaves larger (0.5-1.5 dm, broad) and 

 rounder, thicker, often wavy-margined or crenate, roughish and dark-punctate 

 or pitted beneath ; petioles stouter ; flower 1-2 cm. broad ; seeds glandular- 

 roughened. {Limnanthemum Britton ; L. trachyspermum Gray.) — Ponds 

 and streams, N. J, to Fla. and Tex. 



3. N. PELTATUM (S, P. Gmel.) Britten & Rendle. Stout and branching; 

 petioles hearing no spur-like roots; cxtrolla large (2-3 C7n. broad), bright yellow, 

 the segments somewhat fringed ; seeds with fringe-like margin. {Limnan- 

 themum nymphoides Hoffmannsegg tSb Link.) — Ponds about Washington, D. C. ; 

 often cultivated. (Introd. from Eu.) 



APOCYNACEAE (Dogbane Family) 



Plants almost all with milky acrid juice, entire chiefly opposite leaves without 

 stipules, regular 6-merous and b-androus flowers; the 5 lobes of the corolla 

 convolute and twisted in the bud; the filaments distinct, inserted on the corolla, 

 and the pollen glandular ; calyx free from the two ovaries, which (in our genera) 

 are distinct (forming follicles), though their styles or stigmas are united into 

 one. Seeds amphitropous or anatropous, with a large straight embryo in sparing 

 albumen, often bearing a tuft of down (comose). — Chiefly tropical acrid- 

 poisonous plants. 



* Leaves alternate. 



1. Amsonia. Seeds naked. Corolla-tube bearded inside. Anthers longer than the filaments. 



Plant upright. 



* * Leaves opposite. 



2. Vinca. Seeds naked, CoroUa-tube naked. Plant creeping or traiUng. 



3. Trachelospermum. Seeds comose. Corolla funnel-form, not appendaged. Filaments slender. 



Calyx glandular inside. 



4. Apocynum. Seeds comose. Corolla bell-shaped, appendaged within. Filaments short, 



broad and flat. Calyx not glandular. 



1, AMS6nIA Walt, 



Calyx small. Corolla with a narrow funnel-form tube ; the limb divided into 

 long linear lobes. Stamens inserted on the tube, included ; anthers obtuse at 

 both ends. Ovaries 2 ; style 1 ; stigma rounded, surrounded with a cup-like 

 membrane. Pods (follicles) 2, long and slender, many-seeded. Seeds cylin- 

 drical, abrupt at both ends, packed in one row. — Perennial herbs, with alternate 

 leaves, and pale blue flowers in terminal panicled cymes. (Named for Dr. 

 Amson, physician of Gloucester. Virginia, in 1760, and friend of John Clayton.) 



1. A. Tabernaemontana Walt. Loosely pubescent or hairy when young, 

 soon glabrous ; leaves from ovate-lanceolate to linear-lanceolate, taper-pointed ; 

 calyx-lobes short, awl-shaped ; tube of the bluish corolla little longer than the 

 lobes, the upper part either hairy when young or glabrous, {A. salicifolia 

 Pursh ; A. Amsonia Britton.) — Low grounds. Pa. to Mo., and southw. ; introd, 

 in N. J. May, June. 



2. VINCA L. Periwinkle 



Calyx-lobes acuminate. Corolla-tube funnel -form ; the limb salver-form. 

 Stamens inserted below the throat ; filaments short. Style slender. Pods 

 short-cylindric. Seeds rough, — Smooth trailing hardy plants (or in the Tropics 



