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 Post subject: Re: The Tetragonostachys of Africa and Madagascar
Unread postPosted: Sun Jul 15, 2012 8:45 pm 
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Joined: Mon Jun 25, 2012 8:34 am
Posts: 15
okie wrote:
terrestrial_man -- this is all very interesting reading , but maybe you could show a pic or two , specifically for those of us who are less knowing on the subject :hmz:
You know the saying " a picture is worth a thousand words " :)

I agree! But the only images that I have are of the North American species that I am currently growing and of 3 images taken by Jean Pawek that I have been permitted to post of a species, Selaginella watsonii, in its native habitat. I am hoping that there are readers there who will be able to share images of the plants that they have encountered in their travels of any of the eight African/Madagascaran species covered in this topic.
Perhaps similar to S. Dregei, except for the strobili which are fully developed on its stem and are upright in posture, Selaginella watsonii inhabits rocky outcrops in the mountains of the western United States.
Image
To learn more about the species found in the state of California please visit my topic at
http://cnps.org/forums/showthread.php?t=1653


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 Post subject: Selaginella phillipsiana = S. wightii var. phillipsiana
Unread postPosted: Sun Jul 29, 2012 12:41 am 
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Posts: 15
Of the eight species of the Tetragonostachys that occur in Africa and on Madagascar only the species
Selaginella wightii occurs outside of the area in southern India and on Sri Lanka. Understandably the African and
Asian populations have been classified into two varieties based upon the degree of cilia on the sporophylls.
These varieties are: S. wightii var. wightii, the Asian species, and S. wightii var. phillipsiana, the
African species, which has been recently classified as its own species in The Flora of East Africa, by Bernard
Verdcourt (http://en.wikipedia.org/wiki/Bernard_Verdcourt) and is so regarded by Michael Hassler and Brian Swale in their Checklist of World Ferns website (http://homepages.caverock.net.nz/~bj/fern/).
In an email from Roy Gereau, a specialist in pteriodophytes working for the Missouri Botanical Gardens in the USA, he points out that in Dr. Verdcourt's Flora the species S. wightii does not occur on the African continent but does on Mauritius
whereas Hassler & Swale notes S. wightii as occurring in Tanzania. However, based upon notes by Rolla M. Tryon, Jr. the distinction between S. wightii and S. phillipsiana does not appear to warrant segregation of the
established two varieties without futher delineation, so I am maintaining S. phillipsiana as a variety of S. wightii.

The species is monomorphic in character with the microphylls generally being of the same size and shape
at the same position around a stem. The stems appear to be creeping and possess upright strobili.
Here is an image of the Asian variety taken in Sri Lanka:
http://www.odu.edu/~lmusselm/plant/index.php?todo=details&id=8826

S. wightii appears to be found only in the temperate highlands of southern Sudan, southern Ethiopia, marginally into northwestern Somalia occurring in rocky habitats at 1200-1900 meters (3937-6234 ft)*, western Kenya, and into northeastern Tanzania, as per Mr. Gereau's email of Dr. Verdcourt's findings, found only at two locations at elevations of 900 to 1200 meters (2953-3937 ft). The climate in the areas of occurrence is very moderate varying from averages of 15 C to 25 C (59 F to
77 F). The daily change in temperature can be as much as a 12 degree rise from the morning lows.

Monsoonal rains occur twice during the year with heavier rains occurring roughly during April into June produce
by the southwest monsoon and a lighter monsoonal flow during October into December. High humidities and
fog banks upon the mountain plateaus serve to help cool the area.

The species may be found as cushions sprawling over rocks and among outcrops at elevations ranging from
900 meters (21953 ft) to 2400 meters (7874 ft), as per Mr. Gereau's email of Dr. Verdcourt's findings.
It has been collected on Mt. Kilimanjaro as recently as 2001, being found at 1600 meters (5249 ft).

There are no other images currently available for free view on the net apart from the one noted above.
There are two available herbarium specimens that can be enlarged with their magnification tools.
The best view is of the speciment collected in India by R. M. Tryon Jr. at the Berlin Herbarium
http://ww2.bgbm.org/herbarium/view_large.cfm?SpecimenPK=98227&idThumb=275865&SpecimenSequenz=1&loan=0

and another Indian specimen collected by Robert Wight, who collected in India from 1826 to 1828, is
housed at the New York Botanical Garden Herbarium
http://sweetgum.nybg.org/vh/specimen.php?irn=721083


*from Selaginella in Flora of Somalia vol. 1 (1993) by Dr. Mats Thulin per email from Dr. Thulin. Dr. Thulin
also accepts the taxon designation as Selaginella phillipsiana.

A special thanks to Roy Gereau and Mats Thulin for contributing information to this post.


Last edited by terrestrial_man on Tue Jul 31, 2012 10:50 pm, edited 2 times in total.

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 Post subject: Re: The Tetragonostachys of Africa and Madagascar-in summary
Unread postPosted: Sun Jul 29, 2012 12:53 am 
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Joined: Mon Jun 25, 2012 8:34 am
Posts: 15
Just a word to say thanks to the South African National Parks organization for this forum where I could post up a topic that pertains to the whole of Africa. These small plants that represent species in existence before the division
of the one major land mass that constituted the then ancient earth have remained relatively unchanged over these millions of years while their environment has shrunk and been drastically altered. Their long term survival is a testament to the success of an ancient genetic structure that has proven successful in allowing the species to handle a variety of stressors and environments that would tax most other plants.

While I have only presented some information on each of the relevant species, there is additional information available though not readily so. I have avoided linking to sites that require a fee to view or read pertinent
information or view additional images. Other information is buried away in institutions in costly tomes that
are destined to continue in their accumulation of dust and disuse. Hopefully though, as more persons discover
interest in these types of plants that they will attempt to share with the rest of us that interest and provide the
needed information and images that will enhance our appreciation of these sturdy gems of the plant world.


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