Talinum
Description
Herbs or semi-shrubs (in Malesia glabrous).
Leaves spirally arranged (the lower-most sometimes opposite), linear to obovate.
Flowers in terminal whether or not corymboid thyrsi, or cymosely arranged, seldom axillary or solitary.
Sepals mostly caducous.
Petals mostly 5.
Stamens 5-∞.
Ovary superior;
Fruit globular;
Distribution
S. Africa present, S. and Central America, pantropically
About 50 spp., native in S. and Central America and S. Africa, the two treated species now pantropically naturalized.
Morphology
The inflorescences of the Talinums studied are explained in comparison with the vegetative ramifications, thus in agreement with C. TROLL, who assumes that there is no essential difference between the vegetative and the inflorescential ramification. Their leaves are spirally arranged, the lowermost sometimes excepted. Specimens of T. paniculatum grown at Leyden in winter under low light intensity and short day light produced all opposite leaves and opposite primary inflorescential branches. The flowers of T. paniculatum are arranged in a wide thyrse with a terminal flower (). A change in phyllotaxis, in contrast with the rule of TROLL mentioned, is found in the ultimate dichasial ramifications.
Superficially, T. triangulare is trichasial in the first ramification of the inflorescence (, ). I have tried to bring this in agreement with the inflorescence of T. paniculatum by the following argumentation: the vegetative branches always have 2 basal cataphylls, each with a dormant axillary bud (). The inflorescences lack these cataphylls and buds. The cataphylls easily fall, and mostly the scars are hardly to be found. The cataphylls are also present if the axillary axis is not developed (). In the cultivated specimens these dormant buds developed after the axillary axis was pinched out (), but this only succeeded near the inflorescence. Now the inflorescence may be explained as follows: The main axis ()forms the central flower. The axillary axis (; ) of the leaf (; ), is branched cymosely. From the dormant buds () branches are developed, which are also branched cymosely, and are only slightly poorer than the axillary axis. So the axillary axis () is supposed to represent the first and single racemous ramification of a thyrsus.
Superficially, T. triangulare is trichasial in the first ramification of the inflorescence (, ). I have tried to bring this in agreement with the inflorescence of T. paniculatum by the following argumentation: the vegetative branches always have 2 basal cataphylls, each with a dormant axillary bud (). The inflorescences lack these cataphylls and buds. The cataphylls easily fall, and mostly the scars are hardly to be found. The cataphylls are also present if the axillary axis is not developed (). In the cultivated specimens these dormant buds developed after the axillary axis was pinched out (), but this only succeeded near the inflorescence. Now the inflorescence may be explained as follows: The main axis ()forms the central flower. The axillary axis (; ) of the leaf (; ), is branched cymosely. From the dormant buds () branches are developed, which are also branched cymosely, and are only slightly poorer than the axillary axis. So the axillary axis () is supposed to represent the first and single racemous ramification of a thyrsus.