Handroanthus serratifolius aka Yellow Poui

Handroanthus serratifolius is a tree from the tropics. It belongs to the bignonia family. Common names include yellow trumpet tree and yellow poui. Older sources use the name Tabebuia serratifolia. It is native to Trinidad and Tobago and tropical South America. It grows in Brazil, Bolivia, Peru, Ecuador, and the Guyanas. Wild trees help form the forest's top layer, or canopy. They also grow in savannah, sometimes in stands of this tree alone. They favor ground that drains well over swampy sites.

In Florida gardens, trees reach 25–40 feet [7.6–12.2 metres]. Sources on tropical trees give heights of 98 feet [30 metres]. Wild trees can reach 121 feet [37 metres]. One source gives a spread of 82 feet [25 metres]. The straight trunk may have roots that form broad braces. The smooth bark is gray-tan. Bright green leaves have three to five leaflets. These spread from one point, like fingers on a palm. This leaf form is called palmately compound. The middle leaflet is largest, and the edges have teeth.

The tree sheds leaves in the dry season. Some sources say it loses only some of its leaves. They call it partly deciduous, rather than fully deciduous. Yellow flowers shaped like trumpets grow in groups on bare branches. In Florida, it blooms from late winter to early spring. The bare crown makes the flowers easy to see. Long seed cases, called capsules, have a bean-like shape. They reach about ten inches and split to release seeds. Pollen can cause a moderate allergy response.

Mature trees need warmth, moist conditions, and full sun. Young plants can grow with some shade. They need more light as they grow larger. The tree accepts sandy, loamy, or clay soil that drains well. Sources favor moist soil, but trees withstand drought once established. It also withstands salt spray, so it suits coastal sites. PFAF lists USDA zones 10–12. Temperatures of 41°F [5°C] or lower can kill it. Sources describe its growth as slow or moderate.

Gardeners plant it for shade and its yellow flowers. Its hard, heavy wood serves in homes, bridges, and railway sleepers. The wood resists decay, but marine borers can damage it. Heavy logging puts wild trees at risk. Useful Tropical Plants cites a 2013 assessment that lists it as Endangered. PFAF lists no known edible uses. It notes past uses as medicine, not proven treatments. Sawdust can irritate airways and cause mild skin swelling and soreness.