EXGELMANX — OAKS OF THE UNITED STATES. 3S1 



wood, styles long and spreading or recurved, abortive ovules al- 

 ways near the tip of the perfect seed. The leaves and their lobes 

 are bristle-pointed, at. least in youth ; lobes and teeth acute ; teeth 

 sometimes spinous. Their stamens are usually less numerous, the 

 scales of their cup membranaceous, the inner surface of their nut 

 always tomentose ; the fruit generally matures in the second year : 



We may then arrange our oaks in the following order : 

 QuERCus, Lin. 



I- Lepidobalanus, Endl. : Amenta mascula pendu la; pollinis cellulae 

 0.03-0.04 mm. latae ; flores feminei a masculis distincti : stigmata dilatata. 



A. Leucobalanus : Ovulaabortiva infera vel rarolateralia; stamina 

 plerumque 6-8; stigmata sessilia vel subsessilia; nux intus glabra s. 

 rarissime pubescens. 



* Maturatio annua; nux intus glabra: ovula abortiva infera. 



t Folia decidua. 

 ^. lyrata,^ tnacrocarpa,^ alba, lobata, stellata, Garryana, bico- 

 lor, Michauxii,^ Prinus,* prinoides, Douglasii, undulata.° 

 1 1 Folia sempervirentia. 

 ^. dutnosa,^ Emory i,'' reticulata,^ virens.^ 



** Maturatio biennis ; nux intus pubescens ; ovula abortiva infera vel latera- 

 lia ; folia sempervirentia. 



^. chrysolepis.'^^ 



B. Mel.'VNOb.^lanus : Ovula abortiva supera ; stamina plerumque 

 4-6 ; styli e'ongati demum recurvi ; nux intus sericeo-tomentosa. 



* Maturatio annua; folia persistentia s. subpersistentia. 

 •^- agrifolia,^^ hypoleuca,^^ pumt'la.^^ 



** Maturatio biennis. 



t Folia decidua. 

 ^. palustris, rubra, Sonomensh, cocct'nea,^* ilicifolia, Ge»rgia- 

 na, Catesbtei, falcata, nigra, cinerea,^^ aquatica, laurifolia^^^ 

 heterophylla.^' imbricaria, Phellos. 



1 1 Folia sempervirentia. 

 ^. Wislizeni,^^ myrtifolia.'^^ 



II. Androgyne, A. DeC. : Amenta mascula erecta, basi flores femineos 

 gerentia; pollinis cellulae fere 0.017 latae: stigmata linearia. 



^. densijlora. 



NOTES. 



1. ^uercus lyrata, Walt., extends as far north as Taxodium does, to the 

 banks of the lower Obio in Illinois. 



2. ^. macrocarpa, Michx.,is extremely variable in th»-size of its acorns, 

 and especially in the depth and the margin of its cup, which sometimes 



