F'AGACEAE. 33 
Blakeslee & Jarvis, 338-9, 444, pl.; Cobb, Proc. Amer. Phil. 
Soc., 54:174, pl. 6; Schneider, f. 155. Q. Muehlenbergii. 
Blakeslee & Jarvis, 338-9, 440, pl.;| Brendel, pl. 2; Hitchcock 
(3), 139, f 111-112; ‘Otis, 106. Q. myrtifolia. Trelease (3), 
pl. 12. Q. nigra (Q. aquatica). Trelease (3), pl. 12. Q. palus- 
tris. Blakeslee & Jarvis, 338-9, 448, pl.; Hitchcock (1), 5; 
Otis, 110; Trelease (3), pl. 12. Q. Phellos. Schneider, f. 157; 
Trelease (3), pl. 12. Q. prinoides. Blakeslee & Jarvis, 338-9, 
442, pl.; Hitchcock (1), 5, (3), 19. Q. prinoides rufescens. 
Blakeslee & Jarvis, 442. Q. pubescens. Bosemann, 71; Will- 
komm, 4, 23, f. 22: Q. pumila. Trelease (3), pl. 12. Q. Ro- 
bur (Q. pedunculata). Bosemann, 71; Fant, 11, f. 1; Schnei- 
Ger, f 06,1575" Ward,’ 1:47, £30, 418, 1. 59, 217, f128: ‘The 
on, ta, 1. fo; Willikomm, “7, 22, f..20; Aucearmy 6, plo 2 @ 
rubra. Blakeslee & Jarvis, 338-9, 446, pl.; Brendel, pl. 2; 
Hitchcock (1), 5, (8), 19; Otis, 108; Schneider, f£ 55, 154: 
Trelease (3), pl. 11. Q. Schneckii. Trelease (3), pl. 11. @Q. 
serrata and var. variabilis. Shirasawa, 258, pl. 7. Q. sessili- 
flora (held by many as true Q. Robur). Bosemann, 71; Fant, 
11; Schneider, f. 157; Willkomm, 23, f. 21. Q. stellata. Blakes- 
lee & Jarvis, 338-9, 434, pl.; Cobb, Proc. Amer. Phil. Soc., 54: 
174, pl. 4; Hitchcock (1), 6. @Q. texrana. Trelease (3), pl. 11. 
Q. velutina (often referred to as Q. coccinea; Q. tinctoria). 
Blakeslee & Jarvis, 338-9, 452, pl.; Brendel, pl. 2; Hitchcock 
Cryo, (sy; -8oi) C4) 3 938,97 213-1155 Otis, 14465 ieokdaae (3); pL 
10. Q. Wislizeni. Trelease (3), pl. 138. 
Oaks, like poplars, willows and some other es cast off 
many of their twigs by imperfect abscission in the autumn,— 
a norma! and regular process each year on old trees, as 
Areschoug has pointed out in his Biologie der Holzgewachse. 
This self-pruning forms the subject of a communication in 
1865 to the Botanische Zeitung by Rose. Engelmann (Botani- 
cal Works, 391) has indicated the differences in vernation 
shown by species of Quercus, and Diez published a compara- 
tive study of the subject in Flora for 1887. 
