Littleleaf Linden

(Tiliaceae - Linden or Basswood Family)

Form

• medium- to large-sized shade tree
• slowly maturing at about 60' tall by 40' wide under average urban lawn conditions, but often only 20' tall by 10' wide when used as a street tree under urban stress conditions, yet over 80' tall by 60' wide under optimum growth conditions
• upright pyramidal growth habit in youth, becoming rounded oval with age
• medium growth rate (slow growth rate when under stress)

Culture

• full sun to partial shade
• performs best in full sun in moist, well-drained, deep, rich soils of neutral to alkaline pH; somewhat adaptable to less optimum conditions or soils of acidic pH, but not especially urban tolerant (especially to heat, drought, poor soils, restricted root zones, and pollution) and often suffering significant leaf scorch, stunting, and windthrow when transplanted to sites with stressful conditions
• propagated primarily by grafting cultivar stem cuttings onto seedling rootstock
• Linden Family, with numerous diseases (including sooty mold on the foliage) and pests (especially aphids and Japanese Beetles that attack the foliage) that can cause serious cosmetic damage to the foliage; these biotic stresses are often exacerbated under conditions of abiotic stress
• abundantly available in ball and burlap form
• young trees, with their densely twiggy canopy in both Summer and Winter, are subject to windthrow after transplanting, and should be staked for their first three years of re-establishment
• Littleleaf Linden is somewhat sensitive to being transplanted in Autumn, and care should be taken to amend the soil, fertilize, water thoroughly, mulch adequately, and avoid Winter salt spray, to enhance survival chances during the first Winter

Foliage

• emerging light green but quickly transitioning to dark green and semi-glossy on the upper surfaces, ovate, serrated, with a wide cordate base and a short acuminate apex; leaf blade 2.5" long and wide, with a 1" long petiole
• foliage is densely arranged along the thick twigs and branches, casting a dense shade even from young trees
• lower leaf surfaces are a lighter color, and are somewhat exposed as the foliage (with a wide blade base and relatively long petiole for each leaf) flutters in the breeze
• fall color is chartreuse in many years but golden-yellow in the best years, and often colors best when under stress

Flowers

• creamy yellow, moderately fragrant, and attracting numerous bees, in June and early July, as pendulous inflorescences from the very showy, lime-colored, elongated and curving bracts, the latter of which show up well against the dense background of medium- to dark green fully-expanded foliage

Fruits

• small round nutlets with a rough surface, initially pale green, in pendulous clusters from the pale yellow bracts, maturing in Autumn to a light tan color and semi-persistent (along with the curving bracts) into early Winter

Twigs

• stems mature as red-brown, smooth, slightly zig-zag, and densely twiggy, with reddish, shiny, ovoid, prominent Winter buds

Trunk

• branches and the straight young trunk are reddish-brown and very smooth
• bark becomes lightly furrowed and gray-brown after a few years, then develops a dark gray color with prominent ridges and deep furrows with maturity

ID Summary

• ovate leaves are shiny, dark green above and lighter green below, densely arranged in alternative fashion along the dense branches and zig-zag twigs, fluttering in the breezes of Summer
• inflorescences are creamy yellow and fragrant, attracting many bees, hanging from the showy lime-colored curvilinear bracts, in June and early July
• growth habit is pyramidal to tear-drop shaped, formal, dense, and stately, maintaining a central leader for much of its vertical growth, with many dense lateral branches of relatively small caliper from the trunk, often found so densely at the base of the canopy that they appear in whorled fashion around the trunk at about five to seven feet off the ground, becoming less densely arranged in the middle and upper reaches of the canopy

USAGE

Function

• shade, specimen, or focal point tree, noted for its symmetrical branching, pyramidal growth habit, and dense shade
• often inappropriately used as a street tree in locations with poor soils, restricted root zones, and seasonal drought, but properly used as a street tree under conditions where site soil and moisture are more optimal, especially when the cultivar 'Greenspire' is used
• often trimmed into "tree hedge form" in Europe

Texture

• medium texture in foliage and when bare
• thick density in foliage and when bare

Assets

• very formal appearance (symmetrical branching and tight pyramidal growth habit, especially in youth)
• dense shade, with shiny dark green foliage that flutters in the breeze
• mildly fragrant inflorescences in June and early July
• ornamental bracts are lime-colored throughout most of the Summer, and persist into early Winter as tan bracts with miniature round fruits

Liabilities

• not especially urban tolerant, especially when used as a street tree (leaf scorch, windthrow, and decline become evident under stressful conditions; use Tilia cordata 'Greenspire', which is more urban tolerant)
• foliage may be severely damaged on an annual basis by Japanese Beetles, especially when the trees are found as monocultures in the urban landscape
• flowers attract many bees in early Summer

Habitat

• zones 3 to 7
• native to Europe

SELECTIONS

Alternates

• dense shade trees of moderate stature at maturity under average urban conditions (Acer campestre, Acer rubrum 'Red Sunset', Carpinus betulus, Ostrya virginiana, Pyrus calleryana, etc.)
• trees noted for their symmetrical or formal shape, especially in youth (Carpinus betulus, Cercidiphyllum japonicum, Picea abies, Quercus palustris, Zelkova serrata, etc.)
• street trees more tolerant of urban stresses (Acer campestre, Crataegus x lavallei, Koelreuteria paniculata, Malus, etc.)

Variants

• Tilia cordata 'Fairview' - a rapidly growing cultivar, to 60' tall by 25' wide, with foliage that is thicker and slightly larger than average
• Tilia cordata 'Greenspire' - by far the most common cultivar, compact and with a long central leader, to 40' tall by 30' wide, narrowly pyramidal in youth but spreading with age, much more urban tolerant than other cultivars, and therefore the reason for its widespread usage as a street tree or specimen tree

NOTES

Translation

• Tilia is the Latin name for Linden.
• cordata translates as "heart-shaped" (or cordate), referring to the foliage.

Purpose

• Littleleaf Linden is often found as a small- to medium-sized, densely-foliaged shade tree or street tree, with a highly symmetrical teardrop shape and dense branching habit, especially in youth.

Summary

• Tilia cordata is known as a common shade or specimen tree, very symmetrical in shape, pyramidal to oval in outline, densely dark green and shiny-foliaged in Summer, but often overused as a street tree and prone to stress-induced leaf scorch, windthrow, and decline under difficult circumstances.