Corms formed from stolons; was Cleaning bulbs

Jim McKenney
Wed, 08 Jul 2009 06:11:22 PDT
Jane McGary wrote: “Some colchicums, however, are stoloniferous and it's
rather hard to see how they form their offsets, because when you turn them
out, they are just a pile of large and small worm-shaped corms that aren't
connected one to another. They must form new ones at the end of annual roots
that are withered by the time they're ready to lift. It can be hard at first
to figure out how to plant this kind, but if you look closely, you'll see a
little cone or topknot where the next year's leaves and flowers will
eventually come up, and this goes on top, with the corm lengthwise on the



It trying to understand this mode of growth in some colchicums, it helps to
consider what happens in their relatives, the members of the genus Gloriosa.
The corms of Gloriosa look just like the corms of some of these
stoloniferous colchicums, but nothing at all like typical colchicum corms. 



In the case of Gloriosa, the only thing to watch out for in planting the
corms is to be sure the growing tip in beneath the soil (or in contact with
the soil if the corm is not buried). They will grow well if the corms are
placed horizontally under the soil, they will grow just as well if the corms
are inserted vertically into the soil (as long as the growing tip is down in
the soil). They will grow well if most of the corm is left protruding from
the soil into the air – as long as the growing tip is touching the soil. In
a humid environment, it is not even necessary to cover the growing tip:
corms lying on the surface will produce roots which will work their way down
to the soil. 


I have not tried this with those colchicums which produce vermiform (long)
corms, but I would expect them to react the same way. 


These long corms also provide a good example of how what is happening in the
real world does not always respect our well defined  concepts. What are
these storage structures seen in Gloriosa and some colchicums?  Are they
stolons or are they corms? Are they corms which form along stolons? My take
on this is that they are corms which  form stoloniferously (a stolon is
sometimes defined as a horizontal growth from the base of a plant – that’s
the concept I’m evoking here). The metamorphosis from stolon to corm occurs
when the corm-to-be becomes detached from the other parts of the plant
(using Dylan’s concept of modularity as the defining event). But given the
life cycle of the plants in question, it’s not so much a question of the
incipient corm becoming detached from the rest of the plant; it’s more a
matter of the rest of the plant (at least the older parts which formed the
base from which the stolon  emerged) dying and leaving the stolon/corm
detached from the base. 


Incidentally, Gloriosa corms as purchased are actually half corms: the
corms, as they form in the ground, are typically V shaped. The bottom of the

V is where the now dead annual sprout was attached. The two arms of the V
are usually broken apart at the bottom of the V (where the old sprout was
attached)  by the growers and sold separately. The sprout for future growth
is at the tip opposite the place where the now-dead annual stem was


In my experience, the Gloriosa corms generally have two branches. If you
examine  typical colchicum corms, you’ll see that they too have two
“branches” – the “branches” on colchicum corms are traditionally called
“feet” and usually one is much larger than the other and projects sideways
from the corm mass while the other is often little more than a bump on the
opposite side of the corm. 


I’ve seen long-corm colchicums with three branches which are otherwise dead
ringers for yearling Gloriosa corms. 



Jim McKenney


My Virtual Maryland Garden



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