Stamen number

Livia Wanntorp and co-workers (Chapter 9) study the variation in merism in Conostegia (Melastomataceae) and explore how changes in petal and stamen numbers correlate with increases in carpel numbers. 

Stamen number Oligandry (6 stamens or less) = 0 Polyandry = 1... 

Staminode number (female flowers) versus functional stamen number (male flowers) Identical = 0 Different = 1 Lacking = 2... 

SUBFAMILY TRIBE Genera including polyandrous species Stamen number Flowers unisexual (0) bisexual (1) Inflorescence unisexual (0) bisexual (1) Plant unisexual (0) bisexual (1)... 

SUBFAMILY TRIBE species Stamen number bisexual (1) bisexual (1) (1)... 

Dransfield et al., 1995) to more than one thousand (Dransfield et al., 2008a). The ancestral stamen number inferred for the palm family is six, which is also the ancestral number found for monocots as a whole (Nadot, unpubl. data). In four out of five subfamilies polyandry evolved several times from this trimerous androe-cium (with six stamens). The highest number of transitions towards polyandry, but also towards reduction in stamen number (from six to three) is found within subfamily Arecoideae, which include approx, half of all species of palms. It should be noted that flowers of all arecoid palms are unisexual and that almost all species are monoecious. 

Increase in stamen number appears to have occurred in different ways and perhaps in response to different factors in different groups of palms. 

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