530 PROCEEDINGS OF THE ACADEMY OF [Dec, 



fl04. Arabis lyrata L. Add: 

 Newcastle.— Centerville (A. Commons). 



105. Saxifraga yirginiensis Michx. Add: 



Chester. — Marshallton (B. Long). 

 Newcastle. — Centerville (A. Commons). 



107. Rubus frondosus Bigel. Add: 

 ( 'hester. — West Chester. 



Insert: 

 J 107a. Rubus villosus Ait. 



Frequent on edge of dry barrens. All have one-flowered branches, 

 but I cannot distinguish satisfactorily R. villosus enslenii (Tratt.) 

 from the species. The form I assume typical has three distinct 

 leaflets, sharply serrate, others (indicated by asterisk) have leaves 

 1-3-foliate, coarsely toothed, and may be R. invisus (Bailey) Britton. 



Delaware— Fawkes Run* (B. H. Smith); Blue Hill; William- 

 son.* 



Chester. — Serpentine Ridge*; West Chester. 



110. Rosa humilis Marsh. Read: 



There seem to be two tendencies in this species with us, extreme 

 forms seeming quite different, but I find it impossible satisfactorily 

 to separate intermediates. Any lines of separation seem artificial. 

 Both are frequent on open barren and about margin of greenbrier. 



A. Leaves lanceolate to lanceolate-ovate, acutish to acuminate 

 at apex, finely and sharply serrate, 2.5-4 cm. long. Spines slender, 

 straight. Fruiting pedicels slender. Plant low, of drier situations. 

 Probably to be considered typical R. humilis Marsh. 



Delaware. — Fawkes Run; Mineral Hill; Williamson. 

 Chester. — Sugartown Barrens; Cedar Barrens. 



B. Leaves broadly ovate to orbicular-ovate, mostly rounded to 

 acutish at apex, more coarsely serrate, 2-4 cm. long. Spines stouter, 

 somewhat recurved. Fruiting pedicels stouter. Plant taller, of 

 moister situations. Possibly this the R. palustris of Marshall. 



Delaware. Bear Hill; Middletown Barrens; Williamson; Glen 

 Riddle; Wawa. 



Chester. — Paoli; Serpentine Ridge; West Chester; Brinton's 

 Quarry; Unionville. 



— Nottingham Barrens. 



