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Regarding the origin of Sans.powellii

Dear Juan,

Thank you for clearing up the status of Sans.sp. Lavranos 24534 as being the
broad leafed form of Sans.arborescens. The only collection I knew of this
plant was Lavranos 23251, which was illustrated in the Sansevieria Journal.
The plant that Powys (1996) (Sans. Journ. 5 (1): 3, fig. 1) saw on Kiwaiyu
Island appears to be yet another report of it.

I am curious as to what other botanists have suggested as to the status of
Sans.powellii.

It was Horst Pfennig (1977, 1979) that suggested a hybrid origin for
Sans.powellii N.E. Brown and its appearance is indeed intermediate between
Sans.arborescens Cornu and Sans.robusta N.E. Brown. But that appears to be
only part of the story.

According to chromosome counts by Nazeer & Khoshoo (1984), Sans.powellii is
hexaploid (6x) while Sans.arborescens is tetraploid (4x) and Sans.robusta is
diploid (2x). That suggests that Sans.powellii may be a fertile
allopolyploid that arose from hybridization followed by a doubling of the
chromosomes. (6x = 2x + 4x) That is a process called instant speciation.
There are many reported cases of this occurring in plants, both succulent
and non-succulent.

The only other reported hexaploids in the genus are the spoon-leafed species
(Sans.subspicata, Sans.concinna & Sans.dawei) and cylindrical leafed
Sans.cylindrica.

Nazeer, M.A. & Khoshoo, T.N. (1984) CYTOLOGY OF SOME SPECIES OF SANSEVIERIA
THUNB. Cytologia 49 (2): 325-332.

Pfennig, H. (1977) Rasenbildend bis baumartig: die Sansevierien.
Gartenpraxis 1977 (10): 506-511. (English translation in Cact. & Succ.
Journ. Gt. Brit. 41 (3): 56-60 (1979))

Cereusly Steve

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Subject: Re: [SANS] sp. Lavranos 24534
From: Juan Chahinian <Chahinian@AOL.COM>
Date: Mon, 31 Jan 2000 18:19:01 EST
In a message dated 1/29/00 2:19:23 PM Eastern Standard Time,
CEREOID@PRODIGY.NET writes:

<< Sansevieria powellii N.E. Brown originates from eastern Kenya and is
 believed to be a natural hybrid between Sans. arborescens Cornu and
 Sans.robusta N.E. Brown. It is a caulescent species intermediate between
the
 presumed parents in its appearance.
  >>
It was postulated by Pfennig to be what you mention above. some botanists
disagree.
Juan
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