Tree Identification and Selection
Core concepts
Identification rests on binomial nomenclature: genus capitalized, specific epithet lowercase, both italicized; cultivar names follow the species in single quotes and are not italicized (they may also carry a trademark). Work down a diagnostic hierarchy - leaf arrangement (alternate, opposite, whorled), leaf type (simple, pinnately or palmately compound), margin, venation, buds (terminal vs. lateral, valvate vs. imbricate), leaf scars and bundle traces, twig pith and odor, bark, fruit, and form. Dichotomous keys are only as reliable as the character you choose, so always confirm with a second feature.
Opposite arrangement is uncommon: mostly maples, ashes, dogwoods, buckeyes/horsechestnuts, viburnums, catalpa, and fringe tree - the 'MADCap Horse' mnemonic.
Selection is site-first: hardiness and heat zones, soil pH and drainage, salt and deicing exposure, light, available soil volume, overhead utilities, and mature size. Favor species diversity, use natives where appropriate, and avoid known invasives and overplanted monocultures.
Traps
- Common names vary regionally ('ironwood', 'cedar'); questions reward scientific names.
- Confusing variety (a natural botanical rank, italic, preceded by 'var.') with cultivar.
- White ash leaf scars are U-shaped with a notch; green ash scars are D-shaped, flat on top.
- Identifying only by leaves - buds and bark separate look-alikes in winter.
Rule of thumb
Match the tree to the mature space, not the nursery pot: estimate mature height and spread, add clearance for structures and utilities, and confirm minimum soil volume before choosing a species.