This is the detailed list of tree species starting with the letter O.
1. Octopus Tree
Scientific Name: Schefflera actinophylla
This evergreen tree grows from 10 to 13m tall with a diameter of 20 to 35cm. The tree may be erect or leaning with a spreading, dense crown.
The bark is smooth, grayish-green, or green, and the leaf is alternate, appearing whorled sometimes.
Each leaf is oblong and broad with a lustrous green upper surface and a paler lower surface.
The flower is red-colored, borne in showy terminal inflorescences of 10 to 20 plants. The fruit is a purple to red drupe, about 5mm in diameter, produced year-round.
Scientific Name: Nyssa ogeche
Native: North Florida, South-west Alaska
This deciduous tree grows to 18m tall with a diameter of about 77 cms.
The tree may be erect or leaning, often having multiple crooked trunks and a broad swollen base. The bark may be gray or brown with square or rectangular ridges.
The twig is red-brown and slender. The leaves are alternate, simple, ovate, or elliptic. The upper surface is a lustrous dark green, and the lower surface is paler and velvety.
The flower is typically unisexual, produced in rounded, compact clusters in the spring.
The fruit is an oblong or obovoid reddish drupe about 4cm long, borne singularly with papery wings.
Scientific Name: Gymnanthes lucida
Native: South Florida, Florida Keys
This shrub or small tree grows to 10 m tall with a diameter of 20 cm. The tree has a single, erect trunk and a smooth or finely fissured bark.
The twig is green at first with several lenticels and watery sap. The leaves are alternate, simple, and elliptic in shape.
The upper surface is dark green, and the lower surface is paler.
The flower is unisexual, with male and female flowers on the same tree. The petals and sepals are absent, and the flowers blossom from summer to winter.
The fruit is a 3-parted dark-brown capsule.
Scientific Name: Nerium Oleander
Native: Mediterranean Basin
This shrub or small tree grows from 2 to 6m tall with erect stems. The leaves are borne in pairs or whorls of three.
The upper surface is light green and lustrous, becoming duller as it matures. It has white, pink, or red 5-lobed flowers that bloom year-round in clusters.
The fruit is a narrow pair of follicles.
This plant has historically been considered toxic and poisonous.
The plant is frequently planted for ornamental purposes because of its hardy nature and vigorous growing speed.
Scientific Name: Elaeagnus angustifolia
Native: Europe and Western Asia
This deciduous shrub or small tree is 3 to 14m tall and has a diameter of 65 cm. The bark is dark, reddish-brown, and fissured.
The twig is slender and has silver scales, becoming lustrous green as the tree matures with thorny tips.
The leaf is simple and narrowly oblong. The upper surface is grayish-green, and the lower surface is silver and scaly.
The flower is bisexual, silvery-white, and has yellowish sepals. It blossoms from spring to summer.
The fruit is a rounded drupe, green to yellow-brown, and has a scaly surface, maturing from summer to autumn.
6. Olive, Autumn
Scientific Name: Elaeagnus umbellata
Native: Eastern Asia
This small tree is deciduous or semi-deciduous with multiple stems.
The leaves are elliptical with entire margins. It is wavy and has a bright green upper surface with a lower surface that is densely covered with silver to brown scales.
The blade is 5 to 8 cm long and the petiole is short and silvery.
The flowers are borne in clusters of 1 to 7 on the leaf axils. They are fragrant and yellowish-white colored.
The fruit is a reddish drupe with silvery scales on the skin.
7. Orange, Hardy
Scientific Name: Poncirus trifoliata
This shrub or small tree grows to 3.5m tall with a single, erect trunk and zig-zag branches. The twig is stout, green, and flattened with long green stripes.
The leaf is compound, alternate, and widely spaced typically about three leaflets.
The upper surface is dark green, while the lower surface is paler and white.
The flower is bisexual, 3-6cm in diameter, and usually has 4 to 7 sepals and petals that are white in color with numerous stamens.
The flowers blossom in spring. The fruit is yellow and round, 4 to 5 cm in diameter, and matures from summer to autumn.
8. Orchid Tree
Scientific Name: Bauhinia variegata
Native: Tropical Asia
This evergreen or deciduous tree grows to about 8m tall with a single, erect trunk and a rounded crown.
The bark is grayish, smooth at first, and becomes slightly rough as the tree matures. The twig is brownish or gray-brown and hairy at first.
The leaves are alternate and deeply notched. The upper surface is yellow-green, and the lower surface is paler.
The flower is bisexual with five petals colored red, pink, white, or purple with a deep purple or yellow streak at the base.
The flowers blossom in winter. The fruit is a flattened legume less than 2mm thick and tapering.
Hopefully, this guide has helped you identify some new trees, starting with the letter O.
Your suggestions for more species and genera are most welcome.