On 2015-02-09 08:11 PM, Tim Eck wrote: > Is heterostyly the only barrier to self-fertilization? If so, a lot could > be accomplished with a camel hair brush. I've been real quiet lately, and debated whether I should chime in on this topic, alas I think my poorer part won, so here is a lengthy reply... (South African) Oxalis species employ a system of tristyli, that is there are three whorls of styles, two of them bearing anthers and the third the stigma (5 to a whorl). If the uppermost whorl contains the stigma, it is referred to as a longistylar form, mediostylar for the middle and brevistylar if at the bottom. Not all Oxalis species seem to employ tristyli, but it is common in the bulbous forms. (Most Oxalis from the America's are either weedy, i.e. without a bulb, or have more or less a rhizomatous underground structure. Most (all) South African Oxalis have true bulbs, and tristyli is the rule for sexual reproduction. (I presume that there might be exceptions, as always) Only flowers with two different stylar forms can be pollinated to form seeds. Thus if you have two different clones of the same species, but both are of the same stylar form, they are sterile towards each other. Often only one stylar form is available (for example because only one plant/bulb is collected or because one stylar form exhibits better characteristics from a cultivator's point of view (i.e. Bigger, brighter, taller flowers), or the one stylar form is more vigorous than the other and the weaker does not get distributed). Personally I think this is an excellent state of affairs, because it precludes seed forming which could otherwise turn quite a few species real weedy real quick. ( I am still battling to get rid of O. haedulipes. This one is " a local" and managed to get into nearly every pot of plants I have. Luckily the bulbs are quite distinctive and can be culled during transplanting). Also think of the pest O. pes-caprae have become in some parts of the world, and that only by vegetative reproduction. Think of the havoc if it could set seeds as well). Some research has suggested that the pollen size of the different stylar morphs differ, whether it has been proven conclusively, I do not know. Whatever the case, heterostyli might be the only barrier to self fertilization, but alas, a camel hair brush is not going to break through it that easily. To complicate matters, the basic number of chromosomes vary widely between species, with 5, 6, 7, 8, 9 10, 11, and 12 being possibilities. A multitude of ploidy levels are available, sometimes quite restrictive in a particular species, but, as in the case of O. obtusa, about anything is possible(from 2n to 8n plus?). Even plants from the same locality can display different ploidy levels and are thus incompatible. I once saw three very divergent forms of obtusa growing intermingled with each other without any obvious hybrids inbetween. Salter mentions more than 10 species growing and flowering together in nature, without any hybrids seen. Hybrids between species are unknown. Maybe because of lack of effort and interrest, or maybe because there are too many factors inhibiting pollination. Even when my collection exceeded 80 different accessions of O. obtusa (and about 400 for Oxalis in total), natural seed set were rare, and even hand pollination yielded poor results (bad ploidy selections, I think). The only other Oxalis seedlings I've seen (other than obtusa, haedulipes and that pesky corniculata), are from O flava var fabifolia and O. helicoides. I've heard of O. hirta forming seeds, but it does not grow well for me (actually I do not think I've got any left). Nhu mentioned that Oxalis seeds are very short lived. More than 60% of the South African species does not have endospermous seed. The need to either fall in a suitable place or be planted within 24hours to grow. The tiny seedling with two lobes and a small root gets ejected from the seedpod, it starts to grow immediately and it forms true leaves within two days. O. obtusa does have endospermous seed, and it flowers close to the end of the growing season. I suspect they might last longer, and may even germinate the next season, but I have not investigated it or read about it. Maybe a little experiment is called for.... I think this is enough rambling for one night Happy Gardening (or snow shoveling?) Christiaan South Africa