Talk:Caudex

This is not the definition given in Simpson 2005

This is a wrong transcription of the definition. Simpson (2005, not 2006) differenciates caudex from caudiciform stem. Page 551 says:

Caudex. A short, thick, vertical or branched perennial stem, underground at/near ground level. Is a stem/shoot type.

Caudiciform stem. A low (at or above ground level), swollen, perennial storage stem from which arise annual or otherwise nonpersistent photosynthetic shoots, e. g. some Dioscorea spp, Calibanus. Is a stem/shoot type.

Also, in chapter 9 (Plant Morphology) says, page 352:

Rootstocks (underground stems) function as storage and protective organs, remaining alive underground during harsh conditions of cold or drought. When environmental conditions improve, rootstocks serve as the site of new shoot growth, sending out new adventitious roots and new aerial shoots from the apical meristem or from previously dormant buds. Different types of rootstocks have evolved in various taxonomic groups. These include the following: (...) caudex, in which the rootstock consists of a relatively undifferenciated but vertically oriented stem.

Later, same page:

Some aerial stems may function for storage of food reserves or water. (...) Other aerial, storage stems include a caudiciform stem, which is a low, swollen, perennial storage stem (at or above-ground level), from which arise annual or nonpersistent photosynthetic shoots (e.g. Calibanus, some Dioscorea spp.)

Different from pachycaul also. RoRo (talk) 21:37, 3 August 2013 (UTC)

That's an excellent point. For comparison, Hickey, M.; King, C. (2001). The Cambridge Illustrated Glossary of Botanical Terms. Cambridge University Press.{{cite book}}: CS1 maint: multiple names: authors list (link) says "Caudex The stem of a plant, especially a fern or a woody monocotyledon, e.g., a palm.". It doesn't define caudiciform stem. That term seems rather odd, because it would literally mean stem-shaped stem. Hickey & King's section on "storage organs" doesn't use special terminology, but refers to swollen stems, swollen hypocotyls, and rhizomes. Web searches seem to suggest that the Jatropha image on this page is not a typical caudex, but a specialized "thickened caudex". I'll try some edits on the page, which I hope that you have time to look at. Sminthopsis84 (talk) 15:17, 4 August 2013 (UTC)

This is still not the definition from the book. Simpson defines "caudex" as a more or less subterranean rootstock, with not so much differentiation from a typical shoot, vertically oriented, but thickened and functioning for storage: with aerial shoots arising for a growing station and falling again at the end of the growing station, the caudex is the site from where the plant takes its nutrients to growth again every year. A "caudiciform stem" is not subterranean, and is swollen, like the "pachycaul", but caudiciform stem has non-persistent aerial shoots arising from that stem, and pachycaul has perennial shoots (I think you call pahycauls "bottle trees"). Let's see, page 352, starting with same text:

Some aerial stems may function for storage of food reserves or water. (...) Other aerial, storage stems include a pachycaul, which is a woody, trunklike stem that is swollen basally, the swollen region functioning in storage (e.g. bottle trees, Brachychiton spp, and the boojum tree, Fouquiera columnaris).

I could add another example, Ceiba speciosa, the "palo borracho", very common in our parks. Photos of "palo borracho" trunk in commons --RoRo (talk) 02:26, 7 August 2013 (UTC)

I think I have to add a correction to my own interpretation of pachycaul, it is not necessarily perennial, it can be a deciduous tree but it is a pachycaul and not a caudiciform stem because it is a trunk, you have the rest of the stem and some perennial shoots over the swollen region, is the habit of a tree. That's what I understand from the text. --RoRo (talk) 02:41, 7 August 2013 (UTC)

Again, another correction I realised later. If a pachycaul has a sector with a storage function, then probably those trees are never perennial, storage tissue, as I understand, is used to sprout again every year (and in extreme xerophytic environments but it seems this is not the case). So it seems what the 3 terms have in common is those plants have storage tissue to resprout every year, but caudex is a more or less vertical and subterranean organ, caudiciform stem is an aerial stem entirely swollen, and pachycaul is a trunk. --RoRo (talk) 11:27, 7 August 2013 (UTC)

Did you mean "never perennial" or "not evergreen"? Yes, all the examples that I can find anywhere of pachycaul are tree-like plants with a thick trunk. There's another term, pachycladus (Latin), pachycladous (English), meaning with thick branches, though the term seems to be quite rare. That would apply to stem succulents like Stapelia. The definition at Pachycaul therefore seems to be less than ideal, "with disproportionately thick stems for their length and few branches" seems to cover the stem succulents as well, and it doesn't match the cited reference. I think it should be changed to "with disproportionately thick trunks for their height, and few branches". Sminthopsis84 (talk) 13:12, 7 August 2013 (UTC)

Yes, I mean evergreen. "pachy-" probably means thick. In Brachychiton says "Several species (though not all) are pachycaul plants with a very stout stem for their overall size, used to store water during periods of drought." Something a little more broad than "with the shape of a bottle", but it seems to me a better delimited definition, as not all trees of a species will be found with that shape, but probably all uses the stem for storage. In Ceiba for example, trunks derived from cutting (not from a seed) don't develop a bottle shape. I think is part of the definition that pachycaul is thick because it is fonctionning as a storage organ. A complete definition of pachycaul could say "trunk, thicker for storage, storage for resprout every year (so all are deciduous), all bottle shaped trees are pachycauls". And somewhere "compare with caudiciform stem and with caudex". It is ok? --RoRo (talk) 13:34, 7 August 2013 (UTC)

And "compare also with lignotuber, another storage stem tipycally swollen and woody". In Simpson (2005) says:

A lignotuber or burl is largely a protective and regenerative stem following fires. Lignotubers or burls are tipycally swollen, woody stems, at or sightly below ground level, from which arise persistent, woody, aerial branches (e.g., some manzanita).

I corrected the example given because in the book it is written like a scientific name (it says Manzanita spp.) but Manzanita is the common name, the scientific name is Arctostaphylos. So there are 4 "compare" articles: caudex, caudiciform stem, pachycaul and lignotuber. --RoRo (talk) 14:17, 7 August 2013 (UTC)