Austrian pine

One of the world's most spectacular flowering trees and, in the same breath, one of its most dangerous invaders. Spathodea campanulata is a large, fast-growing tropical tree native to the moist forests of West and Central Africa (GBIF), carrying a dense crown of glossy compound leaves topped by showy, upturned clusters of big, frilly, scarlet-to-orange, tulip-shaped flowers (the boat-shaped buds hold water). It is glorious - and it is a serious invasive. The African tulip tree is listed among the IUCN "100 of the world's worst invasive species"; outside its native range it has overrun wet-tropical forests across the Pacific, Hawaii, the Caribbean, and parts of Asia and Australia, and its flowers can be lethal to native bees. Plant it ONLY where it is genuinely native or where it cannot escape, and first check that it is not prohibited locally - do not plant it in any tropical region where it can naturalise. It is frost-tender (USDA 10a-11), fast, and wants full sun and moisture; in cold-winter climates it is grown only as a tender container specimen kept frost-free. It is an ornamental, not a food plant.

A dense, conical-to-narrow-pyramidal evergreen tree native to eastern and central North America, prized as a screening and foundation conifer. Flat, fan-like sprays of scale-like, aromatic yellow-green foliage clothe the tree from the ground up, and red-brown bark exfoliates on mature trunks. Wild trees can reach 40 to 60 feet but cultivated plants typically stay near 20 to 30 feet; small urn-shaped cones and dense evergreen cover make it valuable food and shelter for birds.

A medium-to-large native shade tree of central and eastern North America, reaching 50 to 80 feet with an ovate-rounded crown and large, asymmetric heart-shaped leaves. In June it carries pale-yellow, intensely fragrant flowers on pendulous cymes - each cluster hung from a distinctive strap-like leafy bract - that ripen into pea-sized nutlets. The fragrant June bloom is a premier nectar source: Missouri Botanical Garden lists it as attracting bees and butterflies, and the Lady Bird Johnson Wildflower Center flags it as having special value to both native and honey bees.

Once the dominant canopy hardwood of the eastern United States forest - an estimated four billion trees, prized for fast growth, rot-resistant timber, and an enormous annual crop of sweet edible nuts that fed people, livestock, and wildlife alike. In the early 1900s an introduced Asian fungus, chestnut blight (Cryphonectria parasitica), swept through and functionally destroyed it: by the 1950s the species was effectively extinct as a mature forest tree. Surviving root systems still send up sprouts from old stumps, but the blight almost always girdles and kills them before they can grow large enough to flower and reproduce. The honest reality for a gardener is that you cannot reliably grow a mature wild-type American chestnut today. The realistic paths are blight-resistant backcross hybrids from The American Chestnut Foundation or transgenic blight-tolerant lines still being deployed - not a pure wild seedling, which the blight will almost certainly kill.

The American elm is the great vase-shaped shade tree that once arched over Main Streets and town commons across eastern North America - a fast, extremely cold-hardy deciduous tree of 60 to 80 feet whose upright trunk divides into a fountain of high, spreading limbs that meet overhead to form a living cathedral ceiling. That iconic form, and the species' tolerance of wet soil and tough urban conditions, made it the default American street tree for a century. Then Dutch elm disease (DED) - an introduced fungal disease carried by elm bark beetles - swept through in the 20th century and killed the vast majority of mature street and shade elms across the continent. The honest reality for a gardener today is blunt: do not plant the unselected wild species expecting it to survive. If you want the American-elm form, plant a DED-tolerant cultivar bred and selected for resistance - 'Princeton', 'Valley Forge', 'New Harmony', or 'Jefferson' - and say so plainly. Where it does grow, it is fast, hardy to USDA zone 3, and remarkably forgiving of wet ground and city stress.

The only native U.S. holly with both spiny green leaves and bright red berries - an upright, pyramidal, broadleaf evergreen tree that slowly matures to 15 to 30 feet in cultivation (to 50 feet in the wild). Thick, leathery, deep green leaves bear spiny marginal teeth, and pollinated female trees carry showy red-to-orange drupes that ripen in fall and persist through winter as bird food. This is the classic "Christmas holly" of wreaths and decorations.