Around 125, see text.
Kalanchoe //, also written Kalanchöe or Kalanchoë, is a genus of about 125 species of tropical, succulent flowering plants in the family Crassulaceae, mainly native to the Old World. Only one species of this genus originates from the Americas, 56 from southern & eastern Africa and 60 species in Madagascar. It is also found in south-eastern Asia until China.
Most are shrubs or perennial herbaceous plants, but a few are annual or biennial. The largest, Kalanchoe beharensis from Madagascar, can reach 6 m (20 ft) tall, but most species are less than 1 m (3 ft) tall.
The Chinese species is thought to have been either Kalanchoe ceratophylla or Kalanchoe spathulata. Kalanchoe ceratophylla is called 伽蓝菜 in China, not very close in pronunciation: qiélán cài or jia lan cai depending on the romanisation (but the Cantonese 'gaa laam choi' may be closer). The genus Bryophyllum was described by Salisbury in 1806 and the genus Kitchingia was created by Baker in 1881. Kitchingia is now regarded as a synonym for Kalanchoe, whereas some botanists treat Bryophyllum as a separate genus.
Cultivation and uses
These plants are cultivated as ornamental houseplants and rock or succulent garden plants. This plant is known to the Chinese as "thousands and millions of red and purple" (萬紫千紅), and is commonly purchased during the Chinese New Year for decorative purposes. They are popular because of their ease of propagation, low water requirements, and wide variety of flower colors typically borne in clusters well above the vegetative growth. The section Bryophyllum - formerly an independent genus - contains species such as the "Air plant" Kalanchoe pinnata. In these plants, new individuals develop vegetatively as plantlets, also known as bulbils or gemmae, at indents along the leaves. These young plants eventually drop off and take root. No males have been found of one species of this genus which does flower and produce seeds, and it is commonly called, the Mother of Thousands; the Kalanchoe daigremontiana is thus an example of asexual reproduction (not so common for leaves). These plants are the food plant of the caterpillars of Red Pierrot butterfly. The butterfly lays its eggs on the leaf and after hatching the caterpillar goes inside the leaf and eats the leaf from inside.
Toxicity and traditional medicine
In common with other Crassulaceae (such as the genera Tylecodon, Cotyledon and Adromischus), some Kalanchoe species contain bufadienolide cardiac glycosides which can cause cardiac poisoning, particularly in grazing animals. This is a particular problem in the native range of many Kalanchoe species in the Karoo region of South Africa, where the resulting animal disease is known as krimpsiekte (shrinking disease) or as cotyledonosis. Similar poisonings have also occurred in Australia.
In traditional medicine, Kalanchoe species have been used to treat ailments such as infections, rheumatism and inflammation. Kalanchoe extracts also have immunosuppressive effects. Kalanchoe pinnata has been recorded in Trinidad and Tobago as being used as a traditional treatment for hypertension.
A variety of bufadienolide compounds have been isolated from various Kalanchoe species. Five different bufadienolides have been isolated from Kalanchoe daigremontiana.  Two of these, daigremontianin and bersaldegenin 1,3,5-orthoacetate, have been shown to have a pronounced sedative effect. They also have the strong positive inotropic effect associated with cardiac glycosides, and with greater doses an increasing effect on the central nervous system.
Bufadienolide compounds isolated from Kalanchoe pinnata include bryophillin A which showed strong anti-tumor promoting activity, and bersaldegenin-3-acetate and bryophillin C which were less active. Bryophillin C also showed insecticidal properties.
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