Acer saccharum is a tree to 40 m tall, young bark silver-gray, mature bark dark gray, peeling in thick irregular plates; sap clear; roots fibrous; long-lived to about 300 yrs; growth pattern determinate (a single bout of stem and leaf growth early in season) (Marks 1975); roots associated with arbuscular mycorrhizal fungi (AM) (endomycorrhizae, Zygomycotina, order Glomales, family Endogonaceae) (Decker and Boerner 1997; Carreiro 1999); terminal winter bud narrowly cone-shaped, to 0.6 cm long, about as narrow as twig, red-brown, sharply pointed, with 4 or more pairs of opposite, overlapping scales (Harlow, 1946; Dirr).
Leaves opposite, 8-15 cm long and wide, 3-5 lobed, lobes with few sharp teeth, hairless except for tufts in vein axils below, dark green above, paler below, tips pointed, base round-lobed.
Flowers pale yellow-green, small, in wispy clusters, April-May, wind pollinated, (not reproductive before about 20 yrs).
Fruit dry thin, flat, winged seeds (samaras) joined end-to end, ripens in Sept.-Oct., wind dispersed, seeds eaten by white-footed mice (Peromyscus leucopus) (Ostfeld et al. 1997). Twigs, buds and seeds eaten by squirrels (Martin et al. 1951). Seeds apparently do not persist more than one year and generally need disturbed sites in which to germinate (Hughs and Fahey 1988).
Wetland status: FACU-.
Frequency in New York City: Occasional.
Habitat: Mostly in mature woodlands. Generally uncommon in coastal plain forests. Very shade tolerant, index 10, a tree of undisturbed, closed, upland forests. Tolerates soil pH 5.5-7.3. Moderately drought tolerant. Intolerant of: salt, soil compaction, flooding (Hightshoe 1988; Whitney and Runkle 1981; Baker 1945).
Notes: Cannot use more than 30% full sun for photosynthesis (saturation point) (Hicks and Chabot 1985). At least one study has found correlations between slow growth and shade tolerance. Sugar maple has a relative growth rate of 0.99 compared to a growth rate of 9.24 for Betula populifolia (Grime 1965) Seedlings may persist in the understory for up to 40 years forming a “seedling” bank that can be released by subsequent canopy gaps (Marks and Gardescu 1998). Seedling growth is inhibited by allelopathic effects of asters and goldenrods. Foliage susceptible to gypsy moth and some other insect damage. Some fungi attack weakened trees. Sensitive to salt and air pollution (Burns and Honkala 1990). Grows well on limestone derived soils relatively high in calcium, magnesium, silt and clay (Balter and Loeb 1983). A host tree of the Asian longhorn beetle, Anoplophora glabripennis (see Norway maple).