I could use some Canna edulis. I think my current plants might be C. indica, they didn’t form much of a usable rhizome at all. C. edulis is supposed to make big egg-shaped rhizomes if I’m not mistaken.
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I’ve posted this on two other forums, so here’s a primer on distinguishing most of the edible Dioscorea at a glance:
When talking about leaves, I mean the leaves on the upper portion of mature vines. Leaves on the lowest portion, as well as on young vines, can sometimes develop in a different configuration (usually alternate on a vine that otherwise has paired leaves).
Vines that twist to the right (lower left to upper right: the “Z” twist), with paired leaves:
D. rotundata & cayennensis
D. alata
D. polystachya
D. japonica
D. nummularia
D. hamiltonii
Vines that twist to the right (“Z” twist), with alternate leaves:
D. transversa
Vines that twist to the left (lower right to upper left: the “S” twist), with alternate leaves:
D. bulbifera
D. pentaphylla
D. esculenta
D. trifida
D. dumetorum
Pentaphylla leaves are divided into 5 leaflets, dumetorum into 3, the rest are singular. Trifida leaves are somewhat palmate, and other than the rounded leaflets of pentaphylla and dumetorum, the rest are heart-shaped (with varying ratios of length-breadth and varying degrees of rounded to angular corners). Bulbifera leaves tend to be broad, alata leaves a bit more narrow and often angular, and polystachya leaves narrow & heart lance-shaped.
Trifida, alata and hamiltonii stems have ridges/wings (which can be substituted by corresponding ridges of spines in some varieties of alata). Rotundata, cayennensis, esculenta, pentaphylla and dumetorum stems tend to be spined or prickly to varying degrees; the rest are smooth (though some species, like nummularia, can have prickles at the base). Bulbifera and nummularia have thick round stems in mature vines (bulbifera’s being fluted), polystachya has a square stem (thin, even at full maturity). Dumetorum is highly pubescent/fuzzy.
Bulbifera bulbils range from round to heart-shaped (like the organ) in Asian types, irregular & angular in African types, and can grow to a large size, though small ones are also produced. Polystachya and japonica bulbils can be round or oval, and are always small. Alata bulbils are ovoid to long & irregular (but not angular), and are small to medium sized. Pentaphylla bulbils are small to medium sized and ovoid to horseshoe shaped, and dumetorum bulbils (probably toxic) are spiny. I’m not sure how transversa bulbils are, but only some varieties produce them. The rest don’t usually produce bulbils. Bulbifera is a reliable producer of bulbils, whereas not all varieties of alata produce bulbils, and those that do aren’t usually as productive as bulbifera.
Those are the main distinctions, but there’s always variation among the species listed, never mind those that I didn’t get to list, which should have further differences.
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For more information on Dioscoreas, I’ll post the links to “Tropical Yams And Their Potential”, volumes 1-6:
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Dioscorea esculenta - https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87208469&content=PDF
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Dioscorea bulbifera - https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87208471&content=PDF
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Dioscorea alata - https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87208472&content=PDF
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Dioscorea rotundata & cayennensis - https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87209454&content=PDF
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Dioscorea trifida - https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87208470&content=PDF
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Minor Cultivated Dioscoreas - https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=CAT87209435&content=PDF
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And for the record, yep, everyone here stews them as well. They usually eat it with olive oil, and accompanied by “Jamón de Freír” or “Colén Guisao” (spicy anchovies, I think). I don’t roll like that… I like ‘em mashed and buttered! My favorite is D. rotundata, which makes a floury mash prior to adding butter. D. alata is much softer, almost watery post-stew, and makes a much smoother and less dense mash. I eat the air potatoes the same way, though they’re kinda intermediate between yams and actual potatoes in taste, and are best when freshly fallen/plucked.