178 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



8. AEONIA Medic. Chokeberry. 



Cymes and leavea nearly glabrous. Fruit black 3. A. melanocarpa. 



Cymes and lower surface of leaves woolly. 



Fruit bright red; calyx lobes very glandular 1. A. arbutlfolia. 



Fruit purple black; calyx lobes nearly glandless 2. A. atropurpurea. 



1. Aronia arbutifolia (L.) Ell. 



Swamps and wet woods; frequent. May; fr. Sept.-Oct. Eastern U. S. (Pyrus 

 arbutifolia L. f.) 



2. Aronia atropurpurea Britton. 



Shaded swamps, eastward; infrequent. May; fr. Aug.-Sept. Eastern N. Arner., 

 south to Va. (Pyrus arbutifolia atropurpurea Robinson; P. arbutifolia melanocarpa of 

 Ward's Flora.) 



3. Aronia melanocarpa (Michx.) Britton. 



Region of Fourmile Run; perhaps elsewhere. May. Eastern N. Amer. (Pyrus 

 melanocarpa Willd.) 



4. AMELANCHIER Medic. Shadbush. Serviceberry. Juneberry. 



Leaves short-pointed; hypanthium (the combined calyx tube, receptacle, and ovary) 

 small, 2.5-3 mm. in diameter, bell-shaped, not constricted below on the young 

 fruit; sepals broad, oblong-triangular, obtuse or abruptly acute or short-pointed, 

 reflexed from the base at time of falling of .petals; petals 10-14 mm. long; tree 



or shrub 1. A. canadensis. 



Leaves rounded at the tip; hypanthium 3-5 mm. in diameter; sepals narrow, triangu- 

 lar or lanceolate, acute, erect or recurved from the middle at time of falling of 

 petals; petals 7-9 mm. long; shrubs. 

 Hypanthium saucer-shaped, constricted below on the very young fruit; sepals 

 recurved from the middle at time of falling of petals; top of the ovary woolly, 

 at least when young; leaves oval, the veins 7-11 (average 8 or 9) pairs; teeth 

 of average leaves 20-28 (32) on each side; stems 0.3-1.2 meters high, growing in 



colonies from rhizome-like bases 2. A. stolonifera. 



Hypanthium bell-shaped, not constricted below; sepals mostly erect; top of the 

 ovary glabrous, rarely slightly woolly; leaves oblong, the veins 10-15 (average 

 11-13) pairs; teeth finer (20) 25-40 (45) on each side; stem 1.2-8 meters high, 

 forming alder-like clumps 3. A. oblongifolia. 



1. Amelanchier canadensis (L.) Medic. 



Dry open woodlands; frequent. Apr.; fr. June. Eastern U. S. (A. canadensis 

 botryapium of Gray's Manual.) 



2. Amelanchier stolonifera Wiegand. 



Rocks at Great Falls; edge of Hyattsville Swamp. Apr. Eastern N. Amer. 

 (A. spicata of Britt. & Brown, Ulustr. FI.) 



3. Amelanchier oblongifolia (Torr. & Gray) Roemer. 



Swamps; occasional eastward. Apr. Me. to S. C. (A. canadensis oblongifolia 

 Torr. & Gray; A. intermedia of Britt. & Brown, Illustr. Fl.) 



Wiegand has identified as A. laevis Wiegand specimens from Bladensburg and 

 Fourmile Run collected by Steele, and adds that they show affinity with A. cana- 

 densis. 



5. CRATAEGUS L. Hawthorn. Red haw. 



Leaves conspicuously triangular-cordate, glabrous 1. C. phaenopyrum. 



Leaves not triangular-cordate, glabrous or pubescent. 

 Petioles about 1 mm. long 2. C. uniflora. 



