General Description | A small deciduous tropical tree native to South America, with showy clusters of flowers that can occur multiple times per year. It is often planted as a specimen tree in landscapes and gardens. This plant is ideal for its tolerance of drought, fast growth, and relatively few pests. |
ID Characteristic | Identifiable by its small size, ridged bark, and large numerous clusters of white flowers with yellow throats that occur when the tree is leafless. When in leaf and before flowering, Tabebuia roseo-alba can be identified by the trifoliate composite leaves in a bright rich green colour, and the pod-like flower buds that extend on long pedicels from the branches. After flowers and leaves have dropped, the identifying characteristic are the long thin fruits. |
Shape | Has a generally pyramidal canopy form. Growth is upright with a central leader, with a low tendency towards codominant stem growth. |
Landscape | In urban areas it is commonly used as a street tree and ornamental landscaping tree for its smaller size, blooms, and little need for frequent watering. It is also commonly used in landscape restoration because of the aforementioned qualities, as well as its fast propagation and growth. |
Propagation | Seeds can be harvested from mature fruits when they have opened, or picked and left in the sun until opening has completed, and planted immediately in organic clay substrate. Germination takes 8-18 days and best results occur between 20 to 35 degrees Celsius. Seedlings can be transplanted to larger pots when they are 4-6cm in length, and are ready for planting in their final intended location in 3-4 months. The seeds store longer if kept in a refrigerator, and it is recommended for best germination results that seeds be used within six months. |
Cultivation | This tree thrives in full sun to light shade in stony, well drained soils. Low to medium water requirements and highly drought tolerant. Pruning when the tree is young is recommended for it to develop a strong structure. As it is known to occur naturally in limestone based soils, it may tolerate slightly more alkaline soil conditions. |
Pests | No commonly occurring pests or diseases, but the bark is prone to lichen growth, which is only cosmetic and does not harm the tree. |
Notable Specimens | Jardim Botanico do Rio de Janeiro (Rio de Janeiro Botanical Garden) Rio de Janeiro, Brazil. |
Habitat | Tabebuia roseo-alba is known to exhibit heliophyte and selective xerophyte characteristics. It can be found in semi deciduous primary and secondary forests, on rocky outcrops, most commonly limestone based substrates. It most often occurs as a single tree. |
Bark/Stem Description | Young bark is mainly smooth and lighter brown, but develops a highly fissured texture and increased thickness when older. Mature bark is medium to dark brown in colour, though it is known anecdotally to appear nearly black in urban areas with high air pollution. New branch growth is light yellow-green. It exhibits dichotomous branch growth (equal division of a terminal bud.) Trunk diameter averages 40-50 cm in mature trees. There is no colour differentiation between the hardwood and sapwood. |
Flower/Leaf Bud Description | Flower buds smooth, green and enlongated 1.5-2cm in length, extending from 1-2cm yellow-green pedicels. |
Leaf Description | Trifoliate composite leaves, 6-11cm long and 4-6cm wide, with a slightly larger middle leaflet. Medium green in colour, ovately shaped with an entire margin and pinnate veining. Petioles and petiolules are round and green. The leaves are lightly pubescent on both sides. The terminal buds are 6mm-8mm, greenish brown and pointed. No colour change occurs in the leaves before abscission. |
Flower Description | The corollas are whitish-pink trumpet shaped flowers with yellow throats 7-17cm long, with 2-3 broken sepals that occur in large clusters of 7-10. Externally glaborous and internally pubescent. The bloom schedule depends on the environment the tree is located in. In climates with dry seasons, blooming occurs after the tree has shed its leaves. Flowering period is from July to October and lasts 2-3 days. This species is allogamous (cross pollinating), and relies on pollinating insects. |
Fruit Description | The fruit is a glaborous dehiscent capsule, thin and cylindrical, approx. 18cm long and smooth. Green and striated when immature and black when mature. They are filled with delicate translucent white and double winged seeds dispersed by wind. One kilogram is equivalent to apprx. 71,000 seeds. The fruiting period typically begins in October. |
Colour Description | When in flower, Tabebuia roseo-alba exhibits strong contrast between dark toned bark and bright white flowers. Leaves are a medium green, and do not exhibit seasonal colour change. There is slight variation in the colour of the bark (ranging from light grey-brown to dark medium brown) depending on location and age of the tree. Flowers are whitish-pink with yellow throats, and their colour does not show any variation. |
Texture Description | Distinguishing textures of Tabebuia rosea-alba are the leaves, which are very finely haired on top and bottom, and the bark, which grows thicker and highly fissured as the tree ages. The flowers are glaborous (smooth and shiny) on the exterior and lightly pubescent on the interior. |