plant that grows from a relative of the Yam family?

David Hershey dh321 at excite.com
Sat Feb 8 20:52:44 EST 2003


What book defines rootstock as "the stock from which the roots, stems
and leaves arise"? You seem to be making up your own definition and
creating a new plant organ, the stock, that is neither root, stem or
leaf.

Gray's Manual of Botany defines rootstock as "a rhizome." 
Bailey's Manual of Cultivated Plants defines it as "same as rhizome." 
Hortus Third defines it as "subterranean stem, rhizome."
Rost et al's 1979 Botany text defines it as "an elongated,
underground, horizontal stem."

Newer botany texts I consulted don't define rootstock or define it
only in the context of grafting.

You keep saying I "should look at the actual plants first hand." Have
you examined every known species of Dioscorea to determine of they
have tubers or storage roots?

What book defines corm as "A true corm is a tuber covered by a tunic,
as in the Crocus."?
Not all corms have a tunic:
http://virtual.clemson.edu/groups/hort/sctop/geophyte/type.htm#corms

"Tubers" of tuberous begonia and cyclamen do not fit the common
definition of tuber as a swollen
tip of a rhizome. They are enlarged hypocotyls:
http://virtual.clemson.edu/groups/hort/sctop/geophyte/type.htm#enlarged


David R. Hershey





"Cereoid+10" <cereoid at prodigy.net> wrote in message news:<VfM0a.476$7G.347 at newssvr19.news.prodigy.com>...
> Rootstock is the stock from which the roots, stems and leaves arise.
> What is so confusing about that?
> The old definition is the original correct definition.
> 
> You seem to be getting the definition backwards. Stock is the base word to
> the term not root. You insist upon making thing far more complicated than
> necessary. Maybe you should stick to chocolate bars and stop trying to
> confuse everybody. Just because malaprops tend to become common usage by the
> great unwashed and eventually get listed in dictionaries, that doesn't mean
> they are correct usage of the terms. Common usage can be nothing but bull
> shit. Tubers have even been mistaken for bulbs in common usage.
> 
> Yes, there is more than one type of tuber even though the terminology has
> not been developed to define all of them thoroughly. Various types of tubers
> can have the growing points on their surface, forming a ring or restricted
> to the apex, depending on the species. A true corm is a tuber covered by a
> tunic, as in the Crocus. The tuber of Cyclamen and tuberous Begonias lack
> any tunic.
> 
> Saying epigeal tubers or tubers in leaf axils are not "true tubers" is
> nonsense. There is no reason to believe that tubers can only be subterranean
> organs.
> 
> As I have said before, you should look at the actual plants first hand
> before waxing pedantic over references based on second and third hand
> information. You might actually learn something!
> 
> 
> David Hershey <dh321 at excite.com> wrote in message
> news:7039c6ef.0302061640.771b2880 at posting.google.com...
> > Rootstock is one of several botanical terms that have multiple
> > definitions. You seem to be referring to the old gardening definition
> > of rootstock as a synonym for rhizome or underground stem. Using
> > rootstock as a term for a stem is obviously confusing and therefore
> > undesirable.
> >
> > The more useful definition of rootstock is the root bearing part of a
> > grafted plant. However, even when applied to grafting, rootstock is
> > somewhat misleading. Less misleading terms are understock or stock. A
> > stock may consist solely of root tissue. However, a stock is usually
> > going to consist mostly of root tissue with a small amount of stem
> > tissue. The stock of a topgrafted fruit tree will contain considerable
> > stem tissue. A stock may include an underground stem but usually it
> > will not. About the only plant with tubers that is occasionally
> > grafted is potato. Tomato is grafted on potato as a novelty or for
> > research.
> >
> > I mentioned several botanical sources, not just Websters Dictionary.
> > You mentioned no sources. Katherine Esau was a well respected plant
> > anatomist. The root chapter in her textbook, Anatomy of Seed Plants,
> > 2nd ed. says Dioscorea has "storage roots." Maybe Esau, Hortus Third
> > and the half dozen college botany textbooks I consulted are wrong and
> > Dioscorea does have tubers and not storage roots as you contend. If
> > so, where is some published proof of that? I checked Simpson and
> > Ogorzally (1986) which says there is controversy whether Dioscorea
> > storage organs represent stem or root tissue.
> >
> > Terms for modified stems are not uniformly defined and are often
> > confusing. There seems to be more diversity in underground stems than
> > can be accomodated by the handful of terms commonly used. Tuberous
> > root and tuber are particularly confusing terms. The term storage root
> > seems to be preferred over tuberous root in botany textbooks and is
> > certainly more accurate.
> >
> > There are different definitions for tuber. Some authorities restrict
> > tuber to a swollen underground organ that develops from a rhizome or
> > stolon. By that definition, tuberous begonia and cyclamen do not
> > produce tubers although they are commonly called tubers. Cyclamen is
> > often referred to as a corm as well. Their storage organs develop
> > mainly from the hypocotyl and have a vertical orientation, not the
> > horizontal orientation of a "true" tuber. They are sometimes termed
> > tuberous stems instead (Hartmann and Kester 1983). However, that term
> > adds additional confusion. The aerial tubers of some Dioscorea species
> > are also not "true" tubers and are sometimes termed tubercles or
> > bulbils.
> >
> > David R. Hershey
> >
> >
> > References
> >
> > Hartmann, H.T. and Kester, D.E. 1983. Plant Propagation: Principles
> > and Practices. Englewood Cliffs, NJ: Prentice Hall.
> >
> > Simpson, B.B. and Ogorzally, M.C. 1986. Economic Botany: Plants in Our
> > World. NY: McGraw-Hill.
> >
> >
> >
> >
> > "Cereoid+10" <cereoid at prodigy.net> wrote in message
>  news:<uV40a.704$kR2.658 at newssvr16.news.prodigy.com>...
> > > 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 <dh321 at excite.com> wrote in message
> > > news:7039c6ef.0302041326.22733e31 at posting.google.com...
> > > > 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&ie=ISO-8859-1&q=dioscorea+corm&btnG=Googl
> > > e+Search
> > > >
> > > >
> > > > David R. Hershey
> > > >
> > > >
> > > >
> > > > "Cereoid+10" <cereoid at prodigy.net> wrote in message
>  news:<flA%9.3109$LZ6.1357 at newssvr16.news.prodigy.com>...
> > > > > 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 <nobody at ibm.com> wrote in message
> > > > > news:1ait3vc1horkuisq67hljgo2v2tia0433s at 4ax.com...
> > > > > > In article <v3rh869esm5ha5 at corp.supernews.com>,
> > > > > > blair <blair863 at hotmail.com> 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.



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