Robinsonella cordata (Heartleaf Robinsonella) - A slender semi-deciduous gray barked tree to 40 feet tall with 2- to 4-inch-long leaves that are heart shaped with a acuminate tip and covered with dense fuzzy hairs on the undersides. In warm frost-free areas this tree stays nearly evergreen, dropping older leaves just as new ones emerge, but in cooler California areas such as the Bay Area, it can be bare of leaves for a couple months in winter. In spring and sometimes into summer appear the very showy terminal sprays of 3/4 to 1-inch-wide lavender-blue hibiscus-like flowers.
Plant in full sun and irrigate regularly to occasionally - older specimens have tolerated situations receiving little to no irrigation but likely would have grown more lush an attractive with a bit more water. Hardy to short duration temperatures down to around 25° F.
This tree is known from wooded or brushy ravines at 5,000 to 6,500 feet in southern Mexico and Guatemala - some report it as far north as Puebla, Mexico. Robinsonella is a genus of 14 species from South and Central America that was named in recognition of Benjamin Lincoln Robinson, the Asa Gray Professor of Systematic Botany at the Gray Museum at Harvard. Robinson was assistant to Sereno Watson for two years and then replaced him as curator when Watson died in 1892, a post he retained until his own death in 1935.
While little known of it in cultivation in recent times, this tree garnered the attention and praise of a number of plants lovers over the years. In Edwin Menninger's Flowering Trees of the World for Tropical and Warm Climates (published in 1962) Menninger notes that "Southern California had a flurry of excitement in 1953 over the first spectacular flowering of twin trees in front of the John W. Harris residence in Los Angeles. The trees, 15 to 20 feet high and as much across were Robinsonella cordata, with Hibiscus-like flowers - small, bright purple, in dense clusters. Through February and March that year, both trees flowered profusely, giving a "blue cloud" effect. Los Angeles flower lovers were wild when they discovered that no plants were available, and they would have to wait until nurserymen could grow some." Menninger also noted that Paul Carpenter Stanley (1884-1963), the tropical plant specialist at the U.S. National Museum and Field Museum of Natural History and author of the "Trees and Shrubs of Mexico" thought highly of this plant and put it "high on the list of the most beautiful Malvaceae".
In Santa Barbara there are only two known older trees of this species, one in Franceschi Park and the other in Orpet Park, both planted around 1958. Some credit Dr. Franceschi (Dr. Emanuel Orazio Fenzi) with the introduction of this tree, but records indicate that this plant did not make it into the park bearing Franceschi's name until many decades after he left Santa Barbara in 1913 and his subsequent death in Tripoli in 1924. Peter Riedel, a partner of Dr. Franceschi wrote a landmark manuscript titled "Plants for Extra-Tropical Regions: A catalog of the plants that are, have been, or might be grown where the orange and the avocado thrive, including brief mention of others every plantsman should know". This was published after Riedel's death in 1952 and is an incredible work that documents much of the plant introduction work that took place in California around the turn of the 20th century. Riedel very specifically notes those plants that were introduced by Dr. Franceschi, including another species of Robinsonella, the white flowering Robinsonella edentula. While Riedel did list Robinsonella cordata in his book, he did so without crediting Dr. Franceschi and notes that it "is of Durango to Puebla and Oaxaca in Mexico a 4.5-9 m tree with 4-13 cm ovate cordate leaves, not lobed but crenate-dentate, long acuminate, loosely stellate pubescent beneath, the 1.5-2.5 cm petals white or purplish." The tree at Franceschi Park was planted in 1958 and may well have been planted by City Arborist and park caretaker Will Beittel, who also authored a book about Franceschi titled "Dr. F. Franceschi, Pioneer Plantsman".
Our plants are vegetatively propagated from a plant received from Dylan Hannon, Curator of the Huntington Conservatory, from cuttings he took from an older tree at the Los Angeles State and County Arboretum (#56-860-P) which they received from Edwin Menninger and is very possibly a sister seedling to those in Santa Barbara. A tree planted at the Fullerton Arboretum in 2000 by Chris Barnhill is from cuttings from the tree in Orpet Park and was well over 20 feet tall and bloomed heavily for several years prior to being toppled by a wind storm in 2014. Photos on this website of this tree at Fullerton Arboretum provided by Ken Greby. We have a nice specimen of this tree growing on our nursery grounds.
This information about Robinsonella cordata displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.
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