This came up in another thread, and I thought this would be an opportunity for the taro lovers on DG to pool their insight. I've heard that a final identification of an uncommon species requires detailed examination of flowers, but there are a few guidelines I use for casual IDs. I'll post them here. Everyone please add your observations.
Colocasia
leaf surface - matte (fontanesii is an exception)
leaf shape - round or heart shaped/cordate; upper lobes tend to be rounded or point up
petiole position - peltate (the stem joins the back of the leaf away from the edge, not at the edge)
offsets - direct offsets or runners, no autonomous offset rhizomes
cell structure - not dense
Alocasia
leaf surface - glossy or matte
leaf shape - not reliable for ID, though elaborate leaf shapes tend to be Alocasias (e.g., nobilis)
petiole position - not a reliable for ID
offsets - nut-like, autonomous offset rhizomes or direct offsets, no runners
cell structure - denser than Colocasia or Xanthosoma
Xanthosoma
leaf surface - matte
leaf shape - arrow shaped/sagittate (upper lobes split to stem, upper lobes point outwards rather than in or up); a “hem-like” vein follows the leaf edge
petiole position - not peltate; petiole attaches where upper lobes meet
offsets - direct offsets rather than runners or autonomous offset rhizomes
cell structure - denser than Colocasia; not as dense as some Alocasia
What distinguishes Colocasia, Alocasia and Xanthosoma?
Could you also add which do best in water and which in soil? Also a general summary of which prefer sun or shade would be nice. People always want to grow them when they see them but I think a lot of people are not sure what to do with them or avoid them because they aren't sure they have suitable conditions. I know it really does not have to do with the particular IDs, but I think it would be helpful to have it on the same thread?
I grow most of mine in containers in partial shade, and I don't have a pond or water garden. If anyone has that info to share, please do. I don't know if generalizations can be made along genus lines.
It is our experience that with a very lose and fast draining soil, all will grow well with a lot of water. We get up to 160" of rain per year...sometimes a foot at a time. The soil is mostly cinder with some organic matter...not much. In some lower points of the property, where the soil tends to stay moist, the colocasias do best...but the Xanthosmas also do really really well in boggier conditions.
Somebody gave me a great hint on last year. She told me that Colocasias and Xanthosomas can manage pretty well in a water pond, but Alocasias should be kept on dryland.
I dont have very much experience of these in pond yet, but I have two different species of Colocasia babies in my pond right now, and they seem great to me.
But all of them do well in containers and flower bed.
This message was edited Aug 2, 2004 1:20 PM