Re: colocasia non-tubers

Dear Clarence Hester and Tony Avent:

Colocasia esculenta is an extremely variable species.  In Hawaii, where it
probably reached its maximum variation, more than 400 cultivars were grown.
Today about 80 of these remain.  Cultivar proliferation occured due to
microclimate variation and they can be separated into two basic categories:
dry land taro and wet land taro.  Wet land taro is cultivated in flooded
ponds much the way rice is cultivated.

Arum esculentum L. Sp. Pl. 965. 1753. is apparently typified by the
illustration of Arum minus, nymphaea folio, esculentum Sloan (Voy. Jam. Nat.
Hist. 1:  167. 1707, 2: t. 106, fig. 1. 1725), although actual specimens
seen by Linnaeus before 1753 may exist in the Sloan or Clifford Herbaria
(BM).  Linnaeus apparently regarded this taxon as an American species.  It
is probable that it was introduced to the New World after 1492, probably for
consumption by African slaves.  Arum colocasia L. Sp. Pl. 965. 1753. and its
homotypic synonyms, including Colocasia antiquorum (of the ancients), can be
typified by a single leaf specimen in the Linnaen Society of London
herbarium, marked with a symbol for "Central Asia," although Linnaeus
published the habitat as "Cretae, Cypri, Syriae, Aegypti aquosis."  there is
some question of the place of first valid publication of Colocasia
antiquorum var. esculenta Schott ex Seem.  It is commonly attributed to
Schott (Syn. Aroid. 42. 1856, or Prodr. Syst. Aroid. 140. 1860), but I do
not believe that the (1) listing of Colocasia esculenta as a synonym of C.
antiquorum and (2) a statement that "C. esculenta = C. antiq. S. var."
constitute definite indication that the "epithets concerned are to be used
in that particular combination," as required by Art. 33, ICBN.  A parallel
example "of combinations not definitely indicated" is given (Art. 33), "The
combination Eulophus peucedanoides must not be ascribed to Bentham on the
basis of the listing of Cnidum Peucedanoides H.B.K. under Eulophus."
Apparently Seemann was the first actually make the combination.

>From Alocasia, which is very closely related, Colocasia differs in
techinical details of the ovaries and their arrangement.  From the typical
Colocasia esculentum, the variety antiquorum (syn. C. antiquorum), known as
Egyptian taro, differs in the flowerless portion of the spadix being at
least as long as the part occupied by the male and sterile flowers, and in
the spathes being inrolled instead of opening widely.  The tubers of this
variety, inferior to those of var. esculentum, are used as food in Egypt.
Elephant's ears commonly grown as ornamentals include Colocasia esculentum
var. euchlora, which has leaves with purplish stalks and dark green blades
with violet margins.  Colocasia esculentum fontanesii is triploid and has
larger purple veined leaves.  Colocasia esculentum illustris, called the
black-caladium or imperial taro, has large leaves that are purplish blace to
nearly black between the green veins.  And, yes, Colocasia esculentum
fontanesii DOES form tubers.

I do believe the Julius Boos contribution to this discussion has
considerable merit with regard to possible reasons why you are not obtaining
tuber production.  In addition to getting them started very early indoors,
with good bright light and warm temperatures (i.e. > 70F at all times), I
also suggest application of fertilizer that would encourage tuber
production.  If growing the plants aquatically, I have found making golf
ball sized packets of a slow release fertilizer such as Osmocote wrapped and
tied in cheese cloth works very satisfactorily.  Push the cheese cloth balls
into the mud a few inches from the base of the plant.

Hope this is of some help.

Scott A. Lucas
Hawaii Tropical Botanical Garden
P.O. Box 80
Papaikou, HI   96781

-----Original Message-----
From: Clarence Hester <>
To: <>
Date: Thursday, December 04, 1997 4:28 AM
Subject: Re: colocasia non-tubers

>Scott Lucas wrote:
>> Dear Clarence Hester:
>> According to D.J. Mabberley's "The Plant Book" (an excellent reference
>> I highly recommend) the genus Colocasia is comprised of 8 species of
>> tropical Asian TUBEROUS herbs with peltate leaves.  Your Colocasia
>> antiquorum is actually a variety of Colocasia esculenta and produces
>> small tubers that are called eddoes.  Also, your Colocasia fontanesii is
>> properly a cultivar of Colocasia esculenta that was previously described
>> Colocasia violacea.  With this in mind, I am highly suspicious that the
>> reason you are not obtaining tubers on your various Colocasias is due to
>> horticultural problems.
>I don't know if you read the earlier post from Lester Kallus, but my
>experience is not unique.  As to "horticultural problems", this may be
>so, but it is not manifested in any other way with the plants.  For
>example, I've actually had to rip C. fontanessi runners out of the
>ground as they spread prolifically and tend to pop up in all
>directions.  Also, my C. fontanessi always produces many fragrant blooms
>during the
>summer season.  To all appearances, there is not a "horticultural
>problem" that I have observed.  In addition, the plants come back year
>after year, so there's something viable living below the ground. It just
>never takes the form of the typical "corm" found, for example,  when one
>digs up C. esculenta.
>As for C. fontanesii being a cultivar of C. esculenta, maybe so, but
>there appear to be huge differences
>in the growth habits of these two plants.  C. fontanessi appears to
>propogate itself but sending out
>runners some distance from the parent plant.  Also, C. fontanesii does
>well as an aquatic.  I don't
>know that this is true of C. esculenta.
>Have you any direct experience growing these plants? If so, have you
>obsserved corm development in
>C. fontanesii?  I think that's the real question being asked.  I learned
>a long time ago to take anything written in garden books with a huge
>grain of salt.

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