Oxalis debilis in China: distribution of flower morphs, sterile pollen and polyploidy.
OBJECTIVE
Oxalis debilis is a South American tristylous species that is currently naturalizing in China. Based on field observations and herbarium data a report is made on its pollination, morph frequencies, pollen viability, seed set and chromosome number. In addition, a new chromosome count for the species in Africa is provided.


METHODS
Field observations were conducted in six provinces in south-east China. Flower visitors were recorded and nectar sugar was measured with a refractometer. The species' compatibility system was determined by carrying out experimental self- and cross-pollinations on bagged inflorescences. Stigma receptivity and pollen viability was determined using the MTT test.


CONCLUSIONS
Populations of O. debilis in China contain either the mid-style-length morph or the short morph, but not both. Pollination is by nectar- and pollen-foraging bees; pollen viability is low; and seed set in natural and experimentally self- or cross-pollinated flowers is extremely low. Chromosome counts indicate that O. debilis contains diploid and tetraploid forms in its native as well as introduced range, which does not support a previous hypothesis that the predominant vegetative reproduction in this species is an escape from pentaploidy.
Luo
Shixiao
S
South China Botanical Garden, The Chinese Academy of Sciences, Guangzhou 510650, China.
Zhang
Dianxiang
D
Renner
Susanne S
SS
D002681:China; D032461:Chromosomes, Plant; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D051479:Plant Infertility; D011058:Pollen / Q000502:physiology* / Q000648:ultrastructure; D011123:Polyploidy; D012098:Reproduction / Q000502:physiology; D012639:Seeds / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology