The Flora of the Cayuga Lake Basin 175 



2. Ostrya (Michx.) Scop. 

 1. O. virginiana (Mill.) K. Koch. Hop Hornbeam. Ironvvood. 



Gravelly well-drained acid or neutral soils; common. Apr. 25-May IS. 

 Most abundant on the ravine crests of the basin, along the cliffs of Cayuga Lake, 

 and on the hillsides s. e. of Ithaca. 



N. S. to Minn, and Nebr., southw. to Fla. and Tex. ; not common along the coast. 



3. Carpinus (Tourn.) L. 

 1. C. caroliniana Walt. Hornbeam. Blue or Water Beech. 



Moist or sometimes dry, gravelly or alluvial, acid or neutral, soils, in woods or 

 ravines; common. Apr. 25-May 15. 



N. S. to Ont. and Minn., southw. to Fla., Tex., and Kans. ; less abundant on the 

 coast. 



4. Betula (Tourn.) L. 



a. Fruiting spikes slender-cylindric, 6-8 mm. in diam., spreading or drooping on 

 slender prominent peduncles ; wing of fruit distinctly broader than body ; leaves 

 mostly with less than 8 pairs of prominent veins ; bark white or whitish. 

 b. Twigs, petioles, and young leaves glabrous from the first; leaves (4-6 cm. long) 

 glossy, ovate, broadly rounded or subtruncate at base, acuminate, doubly 

 serrate with small apiculate but blunt teeth; petioles slender (0.5 mm. in 

 diam.); twigs sparingly glandular, 1-1.8 mm. in diam.; fruiting catkins 6-9 

 mm. in diam. 1. B. pendula 



b. Twigs, petioles, and often the young leaves, pubescent or puberulent, but often 

 becoming glabrate ; leaves usually dull, less acuminate, the teeth usually less 

 irregular and more deltoid ; twigs almost without glands. 

 c. Average leaves 4-6 cm. long, mostly rhombic with a cuneate base ; veins 

 ascending; petioles 0.6-0.8 mm. in diam.; twigs in the upper internodes 1.5 

 mm. in diam. ; fruiting catkins 6-8 mm. in diam. [B. alba] 



c. Average leaves 5-10 cm. long, ovate-oval with a rounded cordate or rarely 

 slightly cuneate base; veins more spreading; petioles stouter, 0.8-1.2 mm. 

 in diam. ; fruiting catkins 8-12 mm. in diam., the scales with more conspicu- 

 ous tips. 2. B. papyrifera 

 a. Fruiting spikes ovoid or short-cylindric, 10-20 mm. in diam., erect or suberect 

 on short or obscure peduncles ;. wing of fruit not broader than body ; leaves 

 mostly with more than 8 pairs of prominent veins. 

 b. Bark dark, close or breaking into thick plates ; bud scales and twigs strictly 

 glabrous ; scales of the fruiting spikes glabrous, thick and woody, not foliaceous. 



3. B. lent a 

 b. Bark yellowish or gray, lustrous, exfoliating in thin sheets ; bud scales, twigs at 

 least at tips, and nodes puberulent, and with sparse long hairs ; scales of the 

 fruiting spikes pubescent, the tips subfoliaceous. 

 c. Scales of the fruiting spikes subcoriaceous, 5-8 mm. long ; basal part 1-2.5 



mm. long. 4. B. lutca 



c. Scales of the fruiting spikes subfoliaceous, 8-13 mm. long ; basal part 2.5-6 mm. 

 long. 4a. B. lutea, 



van macrolcpis 

 1. B. pendula Roth. White Birch. 



Upland or damp lowland thickets ; occasional. Apr. 20-May 20. 



Knoll near D., L. & W. switchback, Six Mile Creek ; Beebe Lake ; Turkey Hill ; 

 woods n. of Cayuga Heights ; Taughannock Gorge ; Fox Ridge ; s. end of Westbury 

 Prairie ; and elsewhere. 



Native: Que. to Alaska, southw. to Me., 111., and Man. Found also in Eurasia. 



