Common Name: Pink Trumpet Tree
Scientific Name: Handroanthus impetiginosus
Habit: The pink trumpet tree is a small to medium sized tree that can grow 20-40 feet in height with a growth rate of 12-24 inches per year (Gilman and Watson, 2011; SelecTree, 2019). It grows from a small pyramid shape (crown wider at the bottom than it is at the top) to an overall broader, rounder form with age (Gilman and Watson, 2011). At the broadest part of the mature canopy, the pink trumpet can have a width of 30-40 feet (Tabebuia impetiginosa, n.d.). It has a moderately narrow trunk and spindly, flexible branches that tend to resist drooping (Gilman and Watson, 2011). The distribution of leaves and flowers in the canopy tends to be somewhat scant (Mattos, 2012).
Figure 1: The overall morphology of Handroanthus impetiginosus. Note the somewhat sparse canopy, relatively thin trunk and branches, upright branching structure, and the broad, round form. (http://neighborhoodnursery.com/plants/trees/tabebuia-impetiginosa-tabebuia-ipe-pink-trumpet-tree/)
Leaves: The leaves of the pink trumpet tree are dark olive green, palmately compound (leaflets originate from one central point to form the whole leaf), and opposite in arrangement (Gilman and Watson, 2011; Ritter, 2011). Each leaf typically consists of 5 leaflets, but sometimes up to 7 (Ritter, 2011). There are no leaves present during flowering (Schlindwein, Westerkamp, Carvalho, & Milet-Pinheiro, 2014).
Figure 2: Leaves of Handroanthus impetiginosus.
Twigs & Bark: The bark is smooth, grey in color and is hardened and tough with some random patterning. The branches are thin and tend to be flexible but straight and strong (Gilman and Watson, 2011; Ritter, 2011). The bark of the tree has traditionally been used for a variety of herbal medicinal uses (Mattos, 2012).
Figure 3: The bark, trunk, and branches of Handroanthus impetiginosus. (http://berniesgarden.blogspot.com/2010/07/tabebuia-impetiginosa-dwarf-pink.html)
Flowers & Fruits: In the spring the pink trumpet tree sheds its leaves and replaces them with showy, pink/purple flowers (Ritter, 2011). These flowers are considered perfect, meaning there are both female and male organs present in them all (SelecTree, 2019). The flowers are trumpet-shaped, giving rise to the name of the tree (Trumpet Tree, n.d.). These trees may take 3 to 20 years from seed to first floral blossom (Ritter, 2011). After flowering, which occurs in the summer, the trees produce 3-12 inch-long, brown, bean-like fruit pods filled with seeds (http://www.ticotimes.net/2014/02/22/trumpet-trees-again-in-bloom, Bernhardt, 2014; SelecTree, 2019; Gilman and Watson, 2011).
Figure 4: The trumpet-shaped pink flowers of Handroanthus impetiginosus. (https://www.monrovia.com/plant-catalog/plants/2142/pink-trumpet-tree/)
Figure 5: The fruit of Handroanthus impetiginosus. The seed pods are long and thin. They transform from this green color to a brown color as they dry. (http://www.astro.caltech.edu/~vam/treeimages/pink_trumpet.jpg)
Where it’s from
The pink trumpet tree has a large native range that spans through Central and South America from Mexico to northern Argentina (Schlindwein, et al., 2014; Tabebuia impetiginosa, n.d.). It is the national tree of Paraguay (Mattos, 2012). These trees are typically found in Sunset Zones 15, 16, and 20-24, and USDA Hardiness Zones 10 and 11 (SelecTree, 2019; Gilman and Watson, 2011). This means that the lowest tolerable temperature for the tree is about 30°F (https://planthardiness.ars.usda.gov/PHZMWeb/). The tree prefers full sun and a loam soil that can drain and is slightly acidic (SelecTree, 2019). The Pink Trumpet Tree is somewhat tolerant to salts in the soil and is highly drought-tolerant (Gilman and Watson, 2011).
Figure 6: The range (shaded) of Handroanthus impetiginosus in the United States. The US range of the Pink Trumpet Tree is marked in the grey areas. The range is only really seen on the coast of California and more inland Southern California, as well as Southern Florida. Note that this is not a native range. (Gilman and Watson, 2011)
Ecological notes: The pink trumpet tree’s main pollinators are bees of the genera Centris and Euglossa. These bees are strong enough to force the petals of the flower apart revealing the stigma and anthers. At the end of the corolla bees collect nectar and pollinate the flower on the way in, if they have visited another flower, or on the way out if this is their first flower. Because pink trumpet trees produce hundreds of flowers at once they are easy for pollinators to find, but, because so many flowers are present on one tree pollinators could spend the entire day on just one tree. Once pollen from a conspecific (same species) plant has fallen onto the stigma, the stigma closes. The plant likely evolved its narrow opening to limit pollinators to far flying species bettering the chances of cross-pollination. Trigona spinipes are pollen robbers, they use their mandibles to slice through the flower petals near the end of the corolla and steal the pollen. To get pollinated more efficiently the pink trumpet tree flowers in the summer when it loses all of its leaves, therefore no flowers are blocked by foliage. The tree also has a colored ring around the opening of the corolla to help guide pollinators down the corolla. On day one, when the most stigmas are still open, the ring is yellow, as time passes the ring fades to orange and then red. This aids pollinator learning because the yellow color is associated with high volumes of pollen and nectar present on the first day of blooming (Schlindwein, et al., 2014). Cross pollinated flowers produce the most fruit. These papery elongated pods are then carried by the wind and dispersed (Blowing in the Wind, 1999).
The pink trumpet tree has adapted to survive water stress, an important feature for a plant that resides in drought ridden environments. In the absence of an adequate water supply, the pink trumpet tree lowers its water potential allowing it to absorb water for longer periods of time after rain. The plant does lose some xylem conductivity during periods of drought but manages a full photosynthetic recovery when water returns to the environment (Dombroski, De Freitas, Tomczak, Pinto, & De Farias, 2014). The tree loses its leaves in the dry season which helps limit drying out due to open stomata in leaves (Ritter, 2011). The pink trumpet tree has little invasive potential and no serious pests or diseases (Gilmen & Watson, 2011).
What we use it for
The pink trumpet tree has many medicinal properties and is used for the treatment of a plethora of ailments. The leaves and flowers of the tree are primarily made into teas and drank. The bark of the tree has the most medicinal properties and can be found in health stores as tea or in capsules. When ingested the tea or capsules can reduce inflammation and lower fevers, clear toxins, resolve congestion, strengthen the immune system, treat degenerative diseases, dysentery, cysts, tumors, and venereal diseases. Applied directly to the ailment site the tea can be used to help wounds heal faster, treat snake bites, eczema, herpes, and scabies (Mart, 2012). A natural naphtaquinone called lapachol is found within the bark of the pink trumpet tree. Lapachol can be used as a potential cancer prevention drug and to improve the prognosis of cancer patients through anti-proliferative properties (Stuart, n.d.).
The pink trumpet tree’s timber, lapacho, is highly valued for its durability and luster. The wood is in the home for cabinets, interior finishings, and parquet flooring. Outside of the home the wood is used for railroad ties, telephone poles, instruments, and wooden balls. The tree also produces timber known as Ipe. This timber is well liked for its durability, fine texture, and resistibility to termites and fungi. Due to its durability it is often used for the outdoors such as posts, poles, bridges, hydraulics, railway sleepers and heavy construction. Indoors the timber is used for cabinets, flooring, and furniture (Mart, 2012). The tree as a whole is commonly used ornamentally in yards, parks, parking lots, and along sidewalks.
Biographers: Olivia Beck & Jennifer Ebling ’20, BIOL 238: Evolution, Ecology, & Behavior, Spring 2019