styraciflua – ‘flowing gum’ called ‘styrax’ or ‘storax’ (i.e., balsamic oleo-resin; thick, clear, brownish yellow, semisolid or solid with a pronounced aromatic odor)

Native range: Eastern US, Mexico, Central America

Leaves:

• alternate
• simple
• 5–7 palmately lobed
• 4–7.5” long & as wide
• serrulate margin
• petiole 2–4” long (looks like maple, but alternate)
• lobes acuminate
• undersides of the leaves are pale green with a coating of fine white hairs
• aromatic when crushed

Flowers:

• monoecious
• small, greenish inconspicuous flowers have no true petals
• male flowers in several clusters and the female flowers hang at the end of the same stalk
• female flowers in globose heads, ~1/2” diameter (2 styles)
• male flowers in terminal upright clusters, no perianth (4-8 stamens)

Fruit:

• ball-shaped burr-like fruit is aggregate of many individual 2-pronged, woody capsules (seed-bearing sections)
• round
• spiny
• 1–1.5” diameter
• persists through winter
• seeds are winged

Other characteristics:

• deciduous tree 50–150 ft. and 3–5 ft. in diameter
• young trees have long conical crowns, while mature trees have crowns that are round and spreading
• branchlets ~ corky ridges or wings
• grey bark is deeply furrowed into narrow scaly plates or ridges
• fall colors include yellow, purple & red

Relevant info:

• moderate to rapid grower
• lives to 200 yrs
• grows very straight, which makes for good lumber, furniture, musical instrument components, and veneer
• sweetgum refers to the aromatic balsam or gum that exudes from wounds to the tree
  • this gum has been used in the past for a variety of purposes, including chewing gum, incense, perfumes, folk medicines, and flavorings

Ecology & Adaptations:

• native from Connecticut to Florida and Missouri further south to Texas, Mexico and Central America.
• found in moist or wet woods, tidal swamps, along streambanks, in clearings and old fields, and especially in low swampy bottomlands (rich, moist, alluvial clay and loamy soils) where they often form pure stands
• 0–800 m.
• pollinated by wind
  • outbreeding due to wind-pollination is reinforced by self-sterility
• seed dispersal – fruits open to release small, lightweight, winged wind-dispersed seeds, which are also eaten (and ultimately dispersed) by birds, squirrels, and chipmunks
• vegetative regeneration/reproduction – sprouts from roots or root crown following damage to trunk by fire, etc.
• fire tolerant:
  • re-sprouts following fire
  • thin bark leaves tree vulnerable to damage from fire, but basal wounds are covered with gum exudation that protects tree from microbial and insect infestation, as long as the sapwood is not killed
• herbivory defense – compounds such as terpenoids inhibit microbial infestation and deter herbivory
• tolerates saturated soils – shallow, wide spreading root system on poorly drained sites, which facilitates access to oxygen in low-oxygen environments (versus a deep taproot with numerous highly developed laterals developed on well drained bottomland sites)
• low-nutrient conditions – association with mycorrhizae below ground facilitates absorption of nutrients and water
• wildlife:
  • white-tailed deer browse during the fall and winter
  • beavers, mice and rabbits eat the bark
  • seeds are eaten by birds (such as American goldfinch), squirrels, and chipmunks
  • small birds probe inside fruits in winter for invertebrates