Tilia americana is a tree to 40 m tall; 90 cm dbh; may live 100 years; roots shallow, associated with ectomycorrhizae (Brundrett and Kendrick 1988); bark of branches dark gray, older bark fissured; often multiple trunks from stump sprouting.
Leaves alternate, heart-shaped to rounded to 15 cm long, 13 cm wide, tip abruptly pointed, margin sharply, long toothed, green below, tufts of hairs in secondary vein axils seedling leaves palmately lobed.
Flowers pale yellow, fragrant, in loose long-stalked clusters of 6-15, attached to an elongate, stalked bract 8-10 cm; blooms May-June, after leaf-out, insect pollinated, bees, flies (diurnal) and moths (nocturnal).
Fruit shell thick, gray hairy, smooth, 0.5-1 cm, 1-seeded, Sept.-Oct. dispersed by wind, gravity and by animals. Seeds eaten (potentially dispersed) by squirrels (Martin et al. 1951). Most seed killed by insects rodents or fungi. Must overwinter before germinating.
Wetland status: FACU.
Frequency in NYC: Frequent.
Habitat: A forest tree. Grows well on limestone derived soils relatively high in calcium, magnesium, silt and clay (Balter and Loeb 1983). Moderately shade tolerant, shade, index 8 (less so than sugar maple) (Whitney and Runkle 1981). Prefers rich, moist soil, pH 4.5-7.5 (USDA, NRCS 2010) in relatively sheltered areas. Intolerant of flooding, drought, salt, soil compaction (Hightshoe 1988, Baker 1945; Gargiullo unpublished data).
Notes: Seedlings eaten by rabbits. saplings girdled by voles (Martin et al 1951). Sensitive to fire and nitrogen-poor soils. Fallen leaves retain relatively high levels of nitrogen, calcium, magnesium and potassium, contributing to soil nutrients. (Burns and Honkala 1990). Trunks and branches damaged by the larvae of the linden borer, Saperda vestita (Coleoptera, Cerambycidae). A North American longhorned beetle. Foliage is attacked by the linden looper, Erannis tiliaria, (Lepidoptera, Geometridae) during late autumn (Covell 1984). Linden is a favorite host of the gypsy moth larvae (Lymantria dispar). Other serious pests include larvae of two other Geometrid moths, the spring cankerworm, Paleacrita vernata, and the fall cankerworm, Alosophila pometaria. The common names refer to the season during which adult moths lay eggs. Both species hatch at bud break and feed on new leaves (Burns and Honkala 1990; Johnson and Lyon 1991). Larvae of the tiger swallowtail butterfly (lepidoptera) Papilio gaucus also feed on the leaves (Tallamy 2003); American basswood is infected by various fungi including anthracnose (Gnomonia tiliae, Ascomycotina) and some other fungi, most of which do not seriously harm healthy trees. However, exposed wood is easily infected by can be attacked by decay fungi such as the yellow cap fungi Pholiota limonella and Collybia velutipes (Flammulina v.), this is an edible fungus that is grown commercially as “Enotake”, (Basidiomycotina, Hymenomycetes), (Lincoff 1981, Agrios 1988).