Acer 



ACERACEAE 



Acer 



98. ACERACEAE Maple Family $£&ft (Tsu Shu K'o) 

 Trees or shrubs with watery, often saccharine, sap and opposite estipulate Ivs.: 

 fls. small, regular, polygamous or dioecious; petals sometimes wanting; stamens 

 usually 8; ovary 2-celled: fr. flat, splitting at maturity into two 1-winged samaras. 

 2 genera with about 120 species in north temperate regions; both genera and abo.it 

 60 species in China. 



1. Acer Linn. Maple $$ij#ji| (Tsu Shu Shu) 



Lvs. deciduous, mostly simple, sometimes 3-7-foliolate: samara winged only on 

 one side. About 115 species; 58 in China. (The old Latin name.) 



Key to the Species 



Lvs. simple: disk of the fl. intrastaminal. 

 b. Fls. in racemes: wings of samara nearly horizontal: (Sect. 

 Macrantha). 

 Lvs. usually not lobed, ovate or ovate-oblong, 8-14 cm. 



long; margins unequally serrate: andro-monoecious. 1. 

 Lvs. broadly ovate, subcordate at base, 6-12 cm. long, 

 5-lobed, the middle lobes longer than the basal two, 



acuminate; margins doubly serrate: dioecious 2. 



bb. Fls. in corymbs or panicles; disk of the fl. extia-staminal. 

 c. Lvs. 3-5-lobed, or undivided. 



d. Lvs. mostly 5-lobed, sometimes 3-lobed: fls. andro- 

 monoecious. 



e. Lobes of the lvs. entire: nutlets smooth and 



flattened (Sect. Platanoides). 

 Wings of the frs. more than 2 x as long as 



the nutlets: lvs. 8-25 cm. across 3. 



Wings of the frs. less than 2 x as long as 



the nutlets: lvs. 5-13 cm. across 4. 



ee. Lobes of the lvs. serrate (Sect. Spicata). 



Infl. a few-fld. corymb: lvs. finely and 



sharply serrate 5. 



Infl. a many-fld. panicle: lvs. irregularly 



and sparingly serrate 6. 



dd. Lvs. 3-lobed or undivided. 



f. Lvs. definitely 3-lobed. 



Nutlets smooth and flattened; angle of the 

 wings acute: lvs. grayish-pubescent 

 beneath; hairs often stellate: andro- 

 monoecious: fls. in corymbs, on pedun- 

 cles 1-3 cm. long (Sect. Platanoides).. . 7. 

 Nutlets convex, veined or ridged. 

 Single nutlet 3-5 mm. in diam.; wings of 

 each pair of nutlets acutely angled 

 or nearly parallel; wing and nutlet 

 15-25 mm. long: lvs. ovate or ellipti- 

 cal, forwardly 3-pointed or sometimes 

 entire, often glaucous and pubescent 

 along the nerves beneath (Sect. Spi- 

 cata) 



Single nutlet 8-10 mm. in diam.; wings 



228 



A. davidi 



A. grosseri 



A. amplum 

 A. mono 



A. oliverianum 

 A. sinense 



A. longipes 



8. A. buergerianum 



