Re: [Aroid-l] Tubers, corms and bulbs, oh my!

From: "J. Agoston" <agoston.janos123 at gmail.com> on 2010.02.10 at 16:25:23(20561) Wow Jonathan... I just say that rhizome has allways (year-round) roots, like Iris × germanica. This is complicated. Here we say Achimenes and Oxalis triangularis have rhizome too. But it is incorrect botanically. It is a stem covered with cataphylls which store food and water. But they don't have roots all the time, which is not fulfilling the term of rhizome from my point of view. Oxalis have somtimes thickened taproot, which stores food and water too, and under winter storage the root witheres while the so called rhizome grows from the root's nutrients. It is said that rhizomes started to develope storing cataphylls and with time cataphylls become larger and rhizomes become smaller. Evolutionists say this is how bulbs evolved from rhizome. (Jacob - Jäger - Ohmann: Botanical Compendium) It is now clear that Littonia, Gloriosa, Sandersonia have corms (they re-develope yearly, the buds are on the surface, and have a tunic, even if it is papery). Interestingyl Zantedeschia aethiopica have rhizomes if kept green all year, but have tuber if sent to dormancy, at least in my terms. Normally this plant goes to dormancy in nature so it has a tuber. Moreover tubers and rhizomes send out secondary roots. The primary root dies soon after germination, but first the rhizome and the tuber forms. Botanists, the few who wish to investigate such things are also in constant debate. Cyclamen, Sinningia, Begonia × tuberhybrida develop their tubers from hypocotyl. They can grow bigger and bigger from year to year. But they have roots year round, at least cyclamen have. I suggested for botanists to brain storm a little regarding vegetative storage organs, but they don't find it interesting. They can make more money and reputation with taxonomic researches. I also have debate regarding Corydalis solida. It looks like a corm (re-grows every year, have a papery tunic, eye is on the surface), but it doesn't re-grow from the basal internode as real corms do, it re-grows like a bulb, from inside. We consider it a transition between corm and bulb. As it doesn't have any influence on the market, and it is not insipiring botanists so much remains a mystery. Another unanswered mystery of life. Jan HTML +More Z5a, Hungary --0016e65b60a83ba426047f417b89----==============w01705742499733021=

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