The Tetragonostachys of Africa and Madagascar

[terrestrial_man]

In Volume 42, printed in 1955, of the Annals of the Missouri Botanical Gardens, is the current definitive work on the global community of Selaginella species found in the subgenus Tetragonostachys titled SELAGINELLA RUPESTRIS AND ITS ALLIES by Rolla M. Tryon, Jr., who was, at the time, an assistant curator of the herbarium at the Missouri Botanical Gardens. This work explored just about every facet of the species and included a limited photographic look at each taken of herbarium samples. Since Dr. Tryon, Jr.'s work some change in the nomenclature of some species has occurred, as well as the discovery of new species, mostly of Mexican origin, that has added to the number of species, 43, which he listed in his publication. Currently 51 species and 1 natural hybrid have been accepted into the subgenus though some additional natural hybrids may exist (in the American Southwest).

In the region of Africa and Madagascar Dr. Tryon Jr. identified 8 distinct species:
S. Balansae, S. caffrorum, S. Dregei, S. echinata, S. nivea, S. njam-njamensis, S. proxima, & S. wightii.

(The complete issue of Volume 42, 1955 of the Annals of the Missouri Botanical Gardens can be downloaded into
PDF format at this site http://botanicus.org/bibliography/b12973130.)

[terrestrial_man]

According to Joan Bibiloni, of Malloreca, Spain, Selaginella balansae arose during the Late Cretaceous, sometime within 65.5 to 99.6 million years ago, from an ancient African or Asian species, though possibly from Jurassic stock that arose on the Pangaea continent. (http://mundani-garden.blogspot.com/2011/02/woodwardia-radicans-giant-of-rain.html). This monomorphic (microphylls (leaves) are similar in size and shape all around the stem) species has been allied to the Selaginella group ARENICULAE by Rolla M. Tryon, Jr. in his 1955 treatise in the Annals of the Missouri Botanical Gardens. This image,
http://gardenbreizh.org/photos/karlostachys/photo-205337.html illustrates its monomorphism. While no strobili are present, I would think that they stand upright on the
branches as do other members of the group Areniculae to which it is allied.

The species is an endemic to Morocco, as this map http://maps.iucnredlist.org/map.html?id=164220 illustrates. The species is found on siliceous rocks at an elevation that ranges from 200 to 1200 meters (656 to 3937 feet).

The populations of the species found in the Atlantic coastal mountains are bathed by cooling moist winds.
http://www.teline.fr/eng/Photographs/All-Families/Selaginellaceae/Selaginella-balansae

[terrestrial_man]

This mat forming species found across central and southern Africa from Angola northeasterly into Burundi, Tanzania, Kenya and Uganda and southward into South Africa and Lesotho, is found growing in montane
outcrops at an elevation of 800-1900 meters (ca. 2625-6233 ft) on rocky, gravelly, or cobbly soils found
in crevices of the outcrops. Generally the species is exposed to full sun and dries back only to recover when
sufficient rainfall is present. Occassionally found in shaded spots which may prevent it from drying out
completely.

Currently no images of living plants have been found on the net. The best illustration is of herbarium
samples at the Herbarium of Berlin.

http://ww2.bgbm.org/herbarium/view_large.cfm?SpecimenPK=100454&idThumb=309351&SpecimenSequenz=1&loan=0

Map of locations in South Africa where the species can be observed with relevant taxonomic information
can be found at this website: http://redlist.sanbi.org/species.php?species=3839-1.

[terrestrial_man]

Fairly common in eastern South Africa, this species can also be found northward in Mozambique into Kenya and Uganda. Populations also occur in Angola.
One of the most distintive species in the Tetragonostachys as S. dregei possesses strobili that only cover half
of a stem while all other species have strobili that encircle the stem.
An excellent photographic study of the species can be found here: http://www.zimbabweflora.co.zw/speciesdata/utilities/utility-display-living-images-by-family.php?family_id=208

Map of where the species can be observed in South Africa along with taxonomic information can be found at
this website: http://redlist.sanbi.org/species.php?species=3839-2.

[terrestrial_man]

Interesting, thanks Terrestrial-man

Thanks Oddesy! Glad that there is some interest. I definitely want to elaborate
on each of the species though the relative lack of available information on the net
will make it a bit tedious to accomplish.

[terrestrial_man]

Among the three species of the Tetragonostachys that are native to Madagascar, Selaginella echinata is easily
distinguishable, as its name suggests.

Currently while no images of living specimens are available on the internet an excellent herbarium specimen
can be found at the Herbarium of Berlin http://ww2.bgbm.org/herbarium/view_large.cfm?SpecimenPK=20691&idThumb=229202&SpecimenSequenz=1&loan=0.

Give the image of the herbarium sheet time to load and then left click or use the enlargement on the control
toolbar to get the maximum size. If at first blurry the image will clear up.

What is seen is a dimorphic species where there is a distinct upperside and a distinct lowerside (generally
called an underside). In this species the underside consists of darker colored (in living plants red coloration) microphylls with almost
barb-like looking apical bristles. Though the mounting has prevented the plant from curling up some of the
tips of the stems appear to curl over bringing the barb-like underside over the uppersides of the stems. I
can imagine this species completely curling over in its natural state thereby presenting a rather omnious
appearance to any animal that may consider grazing upon it. But its primary function may be to counter
the effects of dessication.

Apparently (from Selaginella rupestris and its allies by Rolla M. Tryon, Jr., Annals of the Missouri Botanical Garden, Volume 42. printed in 1955) the strobili (this link is to an American species S. hansenii which has
very small strobili which I would think would be the case with S. echinata though Rolla M. Tryon, Jr. does
not mention size http://i152.photobucket.com/albums/s184/jwcimage/Selaginella/Species%20Tetragonostachys/hansenii/hansenii2012P5.jpg ) of S. echinata are dimorphic as well with the
underside sporophylls being larger than the upperside sporophylls. This would suggest that the strobili
of S. echinata do not stand erect as in many species of the Tetragonostachys but rather lie prone.

I would have to presume the species occurs in rather harsh habitat in the Ankaratra Mountains from west of
Toamasina on the north east coast to Isalo National Park in south central Madagascar at elevations ranging
from 500 to 2000 meters (ca. 1640 ft to 6562 ft).

[terrestrial_man]

Selaginella nivea has been recognized as having two distinct subspecies: Selaginella nivea subspecies nivea and
Selaginella nivea subspecies humbertii.

On the African continent, S. nivea subspecies nivea is a rare plant found only in a few locations in Mozambique,
Botswana, and Zimbabwe. It also occurs in southern Madagascar, in the state of Toliara.

In Africa this subspecies can be found growing in exposed sandy places within Colophospermum mopane (http://www.mobot.org/mobot/photoessays/largephotoessay.asp?fldrloc=drytropics&imgorder=0135 )woodlands (http://www.eoearth.org/article/Zambezian_and_Mopane_woodlands?topic=49597). In Madagascar the subspecies is found growing on sandy soils in the subarid
region of the Plateau Karimbola of the state of Toliara. In southwestern Toliara lies the region Hatokaliotsy
where the species is found on or among rocks of the weathered limestone of the Mahafaly Plateau. It can be
found at an elevation ranging from 55 to 258 meters (180 to 846 feet).

Northward at an elevation of 1600 to 2000 meters (5249 to 6562 feet) can be found the rare subspecies
S. nivea subspecies humbertii. It is currently known from only two locations in the south of the state of
Antananariyou upon igneous and metamorphic rocky soils in the Subhumid Climatic Zone. On Mt. Ibity
http://www.mindat.org/photo-401606.html S. nivea humbertii is found growing on west facing
slopes of gneiss or quartz derived soils in sheltered locations.

The species is dimorphic, with an upperside that is distinct from an underside, and with strobili with dimorphic
sporophylls of underside sporophylls larger than upperside sporophylls and suggesting the strobili lie prone on
their substrate and are not borne upright.
Currently no images exist of the subspecies though an illustration may be found here:

http://plantillustrations.org/illustration.php?language=English&id_illustration=52519&height=950&original_size=0&detail=0&text=0


The illustrations numbered C & D are of the subspecies S. nivea nivea. Illustration C shows the
whole plant with its rhizophores while Illustration D shows the microphyll ("leaf") with its abaxial ridge,
marginal cilia, and apical bristle.

[terrestrial_man]

Selaginella njam-njamensis appears to be Africa's most common species of the Tetragonostachys. It can be found from southeastern Mali, northwestern Benin, into central Nigeria, in the west of Cameroon and the Central African Republic, extreme southern Sudan, southwestern Ethiopia, southward in northeastern Zambia, throughout Malawi,
northern Mozambique, and from northern Zimbabwe into eastern Botswana and adjacent northeast South Africa.

While the species is dimorphic, it is only slightly so and may be easily confused with monomorphic species. This
closeness in appearance to monomorphic species may suggest that its habitat is less xeric than that of the more
pronunced dimorphic species. D. J. Humbler, of the Nigerian College of Arts, Science and Technology in Ibadan, Nigeria, in his article titled A Poikilohydrous, Poikilochlorophyllous Angiosperm from Africa, in Nature (#191, pages 1415-1416, published 30 September 1961, notes that the species inhabits thin soil mats on inselbergs
(This is an image of an inselberg in Mali http://en.wikipedia.org/wiki/File:Hand_der_Fatima.jpg)
(monadnocks) and appears to be poikilohydrous (which means that it can recover from being dried out). However,
the species occurs in areas of summer rains that may vary from 750 to 1000 millimeters (30-39 inches) annually,
as well as upon very faulted gneiss outcrops, with feeder springs that flow out into marshes (Imatong Mountains of
Southern Sudan), at elevations that may range from 400 to 1200 meters (1312 to 3937 feet). Some plant associated with its occurrence are: Loudetia simplex, Aloe labworana, Aloe mawii, Vigna racemosa, Euphorbia ramulosa and E. graniticola, Xerophyta species, and assorted annual species.

Like most monomorphic species, S. njam-njamensis has strobili that are upright rather than prone as seems to be the case with the majority of African/Madagascaran species.

Despite its abundance there appears to be no images of living plants on the internet. There is only one fragment of a dried up branch system with rhizophores available. http://sweetgum.nybg.org/vh/specimen.php?irn=501514

There is a drawing of the plant with possible strobili (indistinct) and a microphyll on document page 44 (page
26/30 on toolbar) of this large PDF file. Allow it time to load before attempting navigation.
http://www.sabonet.org.za/downloads/31_nyika/list/a_nyikalist_p19-48.pdf

[terrestrial_man]

Mr Terrestrial man I just want to thank you for your contribution. I am not going to comment now, as I want to take my time reading. A luxury I don't have this moment.

However, thank you

Thank you Meandering Mouse for your comments. I am hoping that this series on these small often overlooked plants will help enlarge the appreciation of these smaller non-flowering plants. I hope to be enlarging upon my
comments when I prepare similar pages in the flora of the Tetragonostachys that I am slowly working on with the inclusion of the list of references that I have used in constructing these posts as I piece together information from
different sources in order to attempt to arrive at a reasonable understanding of the species.

[terrestrial_man]

Apart from repetitive taxonomic notations of the ranking of this species within the family of vascular plants, there is virtually nothing freely available, on the internet, on this endemic species of Madagascar apart from the description in Rolla M. Tryon, Jr.'s description in his 1955 work "Selaginella rupestris and its allies" (page 56) where the species is described as being dimorphic though with ascendent branching (branches off the main stems that grow upward
rather than proned against the substrate) and are distinguished by curved apical bristles on the microphylls (leaves).
Apparently the strobili of this species lie prone as Tryon, Jr. notes that there is a distinct upperside and underside difference in the shapes of the sporophylls (the leaves of the strobili). He also notes that the curved apical bristle is a characteristic that is shared with the species S. Dregei while other characteristics of S. proxima are similar to those found in S. nivea.

There are only 2 relevant links to S. proxima: to an illustration and to the only available herbarium sample that was collected back in 1928.

At
http://www.plantillustrations.org/illustration.php?language=English&id_illustration=52520&height=550&original_size=0&detail=0&text=0
illustration #E shows a whole plant of creeping stems with rhizophores (from which roots arise) occurring along the stems and illustration #F showing a single microphyll (leaf) that is lanceolate in shape with a prominent abaxial ridge (line down the middle of the leaf), marginal cilia, and a strongly curved apical bristle. As the enlargement options on the toolbar at this site does not allow for enlarged viewing of the image I recommend that you save the image to your computer, scan it for viruses (it had none), and then open the image and use the magnification tool on the toolbar (for Windows).

At http://collections.si.edu/search/results.htm?q=record_ID:nmnhbotany_2144989 is the earliest known collected species (the holotype) at the herbarium of the Smithsonian Institute in Washington D.C. (USA). The herbarium sample is shown and can be clicked on to enlarge but any enlargement is blurry and useless for a close examination of the plant. However, the site of collection, in area surrounding Fort Dauphin, and the elevation, 200 to 300 meters (656 to 894 feet) of the area of collection are noted.

In looking at the taxonomic description of the plant by Tryon, Jr. and the illustration, there can be drawn some conclusions about S. proxima. One would be is that the main stems that sprawl along the substrate and from which rhizophores grow out into the substrate are the most dimorphic portions of the plant with the underside microphylls being wider and longer than those on the upperside of the creeping stems. The microphylls that are on those branches that tend to stand upright are probably quite similar in size and shape all around the branches so that any real distinct upperside or underside is not evident.

Another observation would be that because upright branching is occurring in this species is that its habitat is not as severe as for the other two species found in Madagascar as more rainfall and/or higher humidity would enable the plant to successfully produce such branching. The fact of its occurrence in the area of Fort Dauphin only confirms this observation. The wiki of the area of Fort Dauphin http://en.wikipedia.org/wiki/T%C3%B4lanaro charts the average temperature highs and lows as well as rainfall for an annual cycle and shows a climate that is relatively warm year long with moderate monthly rainfall, except during September and October when it dips towards the mid-70 millimeters (3 inches). According to weatherunderground.com at 850PM in Madagascar
the area was encountering moderate winds (which is common in this area), 21 C (70 F) temperatures, and humidity at 88%.

The area of Fort Dauphin is at the southern end of a system of tropical rain forests and has a mountain chain to its west and north. http://photos.wildmadagascar.org/images/Dylan/Fort_Dauphin_airport_view.shtml
illustrates rather steeply rising mountains adjacent to the coastal community. On closer look at the area the habitat appears to be quite rocky, suitable habitats for S. proxima, http://www.africaimagelibrary.com/-/galleries/islands/madagascar/-/medias/bea1ab5e-223c-11e0-985d-5b0826b42aaa-lokaro-bay-near-taolagnaro-fort-dauphin-madagascar and http://www.africaimagelibrary.com/-/galleries/islands/madagascar/-/medias/5ea9def0-223d-11e0-ba76-f1c744de30b4-lokaro-bay-near-taolagnaro-fort-dauphin-madagascar.

[terrestrial_man]

Mt terrestial man, could you please, for blondes like myself give a brief definition of dimorphic and monomorphic?

My pleasure! Here is a link that shows microphylls (leaves) that are monomorphic (= same size and shape) of
the species Selaginella selaginoides (left side images),
microphylls that are dimorphic (= dissimilar size and shape) of two North American species S. peruviana (also occurs southward into Argentina) and S. arizonica with the upperside leaves being smaller and different shaped
than the underside leaves.
Also shown on the right side is S. rupincola comparing the leaf (microphyll) with the sporophyll (the leaf that is found in the reproductive organ of the plant, the strobilus) and illustrates that sporophylls are broader at their
base as they enfold the sporangia in which spores are produced. Incidentally, S. rupincola is closely related to
the Moroccan endemic S. balansae.
http://www.efloras.org/object_page.aspx?object_id=41391&flora_id=1

[terrestrial_man]

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
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.

[terrestrial_man]

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.

[terrestrial_man]

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.

[terrestrial_man]

I have discovered a site that features an in-depth look at Selaginella nivea with a photo of a plant in its habitat.
Also therein is a chart contrasting 5 species of the Tetragonogstachys. This is the work of A. W. & R. R. Klopper
and was published in Bothalia in 2011.
Explore Bothalia at this link http://www.abcjournal.org/index.php/ABC
and check out the article and photo at this link: http://abcjournal.org/index.php/ABC/art ... File/73/73