The term rootsock does not mean the same as true roots. Roostock refers to
the central body of perennial plants and can be rhizomes, tubers, bulbs,
etc.

Webster's (which is not a botanical reference anyway) is wrong. The
rootstock of Dioscorea is a tuber. Often it is fleshy but it can be woody
and caudiciform. None have tunicated corms.

You should look for yourself rather than rely on sources based on second or
third hand information.


David Hershey wrote in message
om...
A rootstock cannot be a tuber because a tuber is a modified stem.

A variety of terms are applied to storage structures of Dioscorea.
Katherine Esau in her Anatomy of Seed Plants text, Hortus Third,
Webster's New Collegiate Dictionary (under yam) and all the college
introductory botany texts I checked all say Dioscorea has a storage
root or tuberous root. Hortus Third also says D. bulbifera produces
aerial tubers, and some Dioscorea species have rhizomes. A few
websites even claim some Dioscorea species do have corms.

Distinctions between types of modified stems, such as stolons,
rhizomes, tubers and corms, are not always clear cut.

Reference


http://www.google.com/search?hl=en&i...orm&btnG=Googl
e+Search


David R. Hershey



"Cereoid+10" wrote in message
om...
Sorry Spammy Davis, Jr. but you have already jumped to wrong conclusions
and
that does not help.

The rootstock of Dioscorea is a tuber not a corm. A corm is covered by a
tunic but a tuber is not.

Dioscorea is a huge genus and even includes a number of cold hardy
species.

The "Sweet Potato" Ipomoea batatas is a "Morning Glory" with tuberous
roots.


I Don't Like Spam wrote in message
...
In article ,
blair wrote:
I was at somebody's house once and they had a big sprawling plant
with
heart
shaped leaves. They said that they grew it by putting a relative of
the
yam
family into the ground and planting it. Apparently you could also
plant a
yam and grow a different plant as well.

Does anyone know what this plant is?
When I was in college, a friend planted a sweet potato in a pot and
let it grow. Later she told her room-mate that it was a "heart-shaped
wandering jew". This was believed until an energetic pet knocked the
pot over, breaking it, revealing the true nature of the plant. As
mentioned earlier, sweet potato is in Convolvulaceae, with morning
glories.

I wouldn't have brought this up, except sitting on my window sill here
at work is a member of the yam family Dioscoreaceae, _Dioscorea
macrostachya_, (dormant right now) the leaves of which are very
similar to the heart shaped leaves of sweet potato. This grows from a
large corm that is quite interesting in appearance. In nature this
corm is hidden underground, but when sold as a houseplant, the organ
is kept above ground for show (some of the larger, older ones resemble
a tortoise shell, at least if you have an active imagination).

So, before we jump to conclusions about exactly what the plant is,
there ARE some members of the yam family kept as houseplants that fit
your description (although, in general, they are a bit pricey, and not
very common except perhaps through specialty succulent dealers).

Sweet potatoes as sold in the US, often called yams (oh the wonders of
misleading common names). Ask your friend if they could allow you to
take a look at the underground stem by brusing away a little soil. If
it looks like a sweet potato, it probably is. Otherwise, my Dioscorea
has a THIN, SINGLE, TOUGH twining vine that comes from the TOP of a
CORM-like structure. If I recall correctly, a sweet potato would
likely have SEVERAL sprouts coming from a VARIOUS POINTS along a
HORIZONTAL TUBER, and those sprouts would tend to be more FLESHY or
SUCCULENT, at least close to the tuber.

Hope this helps.