Chiranthodendron pentadactylon Larreat., a Mexican medicinal plant in the Hanbury Botanical Gardens.

Chiranthodendron pentadactylon is a Mexican tree which also goes by the name of Hand-flower tree or arbol de las manitas (McClintock, 1988). It is called macpaxochitl in nahuatl, from macpal (hand) and xochitl (flower) (Dominguez et al., 1972). This tree is native to the hill region of Oaxaca, Chiapas, Mexico and Guatemala, and widely cultivated for ornament in Mexico (Standley, 1923). Chiranthodendron is a monotypic genus, included in the family of Sterculiaceae, though some authors hold it belongs to the Bombacaceae. A synonymous is Cheirostemon platanoides (Gastaldo et al., 1994). A large specimen of Chiranthodendron pentadactylon is to be found in the Hanbury Botanical Gardens of La Mortola (Ventimiglia); it is only one grown in the open air in Europe (Gastaldo et al., 1994), and was probably planted between 1912 and 1938 (Hanbury, 1938). This specimen flowered and fruited regularly until 1985 and 1986, two years in which frost damaged a lot of plants on the Riviera. The tree lost all its leaves and the tips of its branches. However, it gradually recovered, and now it flowers and fruits again. A proportion of fertile seeds is produced. The present heavily shaded location of the tree corresponds to the forest conditions of its natural enviroment. Flowering time is from May till June. The flowers have a large calix and no corolla. The relevant staminal structure consists of a column of stamens, linked at the base and then splitting into five curved finger-like branches. At full development, the staminal column has a red colour and the anthers are yellow. Little is known about pollination; in its natural environment this is probably due to the interference of hummingbirds or mice and squirrels. The leaves are deciduous, long-petiolate, palmately 5-lobed and deeply cordate at the base, with entire margins and a scurfy tomentum of stellate yellowish brown hairs on the underside. The fruit is a loculicidal capsule. The Hand-flower tree, Chiranthodendron pentadactylon, belongs to Mexican folk medicines. Its flowers were used in infusion by the Toluca people to treat ophthalmic inflammations and hemorrhoids (Barcena, 1876). The flowers are also included in the Mexican Pharmacopoeia (Imbesi, 1964) and in the Mexican medicinal plant list drawn upby Diaz (1977). It appears as a medecine used for heart complaints (Dominguez et al., 1972). Cyanidin 3-glucoside, octacosene, 1-docosanol and -sitosterol were isolated from the flowers; leucocyanidin, luteolin 7-glucoside, luteolin 7-glucuronide, quercetin-3-glucoside, gossypetin, gossypetin-3-glucuronide from the leaves (Dominguez et al., 1972; Harborne et al., 1972). The ethanolic flower extracts were toxic on mice (Dominguez et al., 1972)