New Records of Pteridophytes for Botswana

4 Pages·1997·1.9 MB·English

by  Efren Vega

American Fern
J(
New
Records Botswana
of Pteridophytes
for
Vega, Rodulio Caudales\ and Antonio
EFRfiN SANCHEZ-PfiREZ
was
Isoetaceae encountered
Tiily
schwein-
single species, Isoetes
1
Ophioglossum
species: lancifol-
r
Although the pteridophj^es of southern Africa have been thoroughly and
very capably surveyed (Schelpe, 1970; Jacobsen, 1983; Schelpe and Anthony
new
1986; Burrows, 1990), explorations are adding to knowledge regarding
Botswana
their specific ranges. a semi-arid country situated in the south-
is
central part of the African continent and has three major ecological regions
Okavango and
(Parson, 1993). In the northern region there are the Delta the
ancient lake beds of the Makgadikgali Pans. The southern area comprises the
Kalahari Desert, characterized by sand dunes and scrub and bush savan-
fossil
na. Between the Okavango-Makgadikgali and the Kalahari Desert, an inter-
is
known
mediate zone Hardveld dominated by sandy
ecological as the region,
soils.
The and Botswana have be
records for ferns fern allies in yet to finalized.
we
Herein report the occurrence of four pteridophyte species not yet recorded
new
One them
family
for the region of a representative of a also to
(Fig. is
1).
the records
for
I
Results
The family Isoetaceae contains nine species in South Africa distributed in
all countries of the region with the exception of Botswana, according to Bur-
we
Botswana, found
rows (1990). In our survey of the pteridophytes of Isoetes
new Ophioglossum
Other records include
schweinfurthii a single locality.
at
dimorpha, and Marsilea minuta. Details are present-
Actinoptehs
lancifolium,
mapped
ed below and
localities are in Fig. 1.
Braun Baker.
Isoetes schweinftirthii A. in
mm
and have
Rhizomorphs up 15 in diameter, scales that
are trilobed, to
Each may have up 40
and elongate. plant to
are horny, dark-brown, deltate to
cm
11-38 with persistent orbicular
number, in length,
erect sporophylls in
AMERICAN FERN JOURNAL: VOLUME NUMBER
87 4
(1997)
mm
5-10
bases broad with and The
tapered apices deltate sporangia
ligules.
mm
X mm,
obovate 7-12 6-8
are to orbicular, without a velum. Megaspores
have prominent tubercles on and on
their distal faces are or tuberculate
flat
proximal Microspores
faces. are
alate,
Isoetes schweinfurthii is the only species of this family occurring in Bot-
swana, having been
localized in the southeastern section of the country, north
of Kgale Siding near Gaborone Dam.
the
general distribution includes the
Its
areas of eastern Transvaal in South Africa, Namibia, Zimbabwe, Angola, Mo-
zambique,
Tanzania, Sudan,
Central Africa Republic, Ivory Coast, Senegal,
Moroco and
Madagascar.
Its specific habitats are pools in rocky outcrops. Her-
barium Hansen
voucher: 3401
(PRE).
Ophioglo
lancifolii C. Presl.
I I
Rhizomes cm
up
are elongate, to 5 in length. Roots are thick and horizontal.
mm
X
Vegetative blades
are linear to oblanceolate, or narrowly 15-80
elliptic,
mm.
2-12
Bases
are cuneate, gradually tapering into an elongate pseudo-pet-
mm
and
iole, the apices are apiculate. Fertile blades are 30-150 in length and
are inserted at the base of a sterile blade. Sporangia are in 8-23 pairs.
Ophioglossum
lancifolium is distinguished from two other species of the
genus
occurring Botswana by morphology
in and
of the vegetative blade of the
rhizome.
Vegetative blades are narrowly than
elliptic to linear-lanceolate (less
mm
mm
12 broad) and
in O. lancifolium, 40
elliptic to ovate-cordate (up to
broad) polyphyllum
in O. A. Braun. Ophioglossum
lancifolium, with oval to
linear rhizomes, can be distinguished fi-om O. costatum R. which has or-
Br.,
bicular rhizomes.
Ophioglossum
lancifolium is found in seasonally wet places in the region
of Savuti, north Leopard
of North
Hills in Botswana. generally distributed
is
It
in the southwestern portion of the Cape Region South and
of Africa scattered
VEGA BOTSWANAN
ET PTERIDOPHYTES
AL.:
129
in eastern South Africa to Zimbabwe, Namibia, Angola, Zambia, Malawi, Tan-
Kenya, Uganda,
zania, Zaire, Mali, Ethiopia, Madagascar, Reunion and
the
Comoro
Herbarium
Island. voucher: Jacobsen 3523
(PRE).
dimorpha
Actinopteris Serm.
Pic.
mm
mm
Rhizomes
are 5 in diameter, with pale brown scales up to 5 long.
Fronds
are densely tufted, erect, coriaceous, and dimorphous. The stipes are
mm
glaucous, mostly glabrous, bearing a few linear scales up to 19 long.
Blades are flabellate with truncate bases, and dichotomously divided
into as
many
as 16 glaucous, linear segments. Fertile fronds are longer than vegetative
ones. Segments are entire, but with 5-7 teeth at the apex. Margins usually are
with brown
reflexed, the undersurface having
linear scales.
dimorpha
Actinopteris can be distinguished from the one other related spe-
cies of the genus occurring in Botswana, A. radiata (Sw.) C. Chr., primarily by
morphology and number dimorpha
scale of blade segments. Actinopteris
its
bears a few linear scales, whereas those of A. radiata are lanceolate. Actin-
opteris dimorpha has up to 16 glaucous, linear segments, whereas A. radiata
20-48
has
segments.
Aedume
Actinopteris dimorpha has been collected in the Park in Gaborone
{Hansen 3350, PRE), in the Lepoloke Hills north of Bobonong [Campbell 179.
PRE), in the Aha Hills of the Ngamiland District [Long and Rae 374. PRE), and
in the Kgale Montain in the vicinity of Gaborone [Mott 1015, PRE). dis-
It is
Zimbabwe, Mozambique,
Region South
tributed in the Transvaal of Africa,
Comoro and
Malawi, Zambia, Tanzania, Somalia, Madagascar, the Islands, Re-
The and
union. habitat generally rock crevices boulders.
is
Marsilea minuta
L.
and
Fronds have usually glabrous not
of this species leaflets thinly pilose,
with margins round-
translucent. Leaflets of the floating forms are ovate distal
cm
up
form
ed, entire or shallowly irregular. Stipes of the dry are to 13 in
There
length, the obovate, and distal margins entire or sinuate. are
leaflets
(1)2^ sporocarps per these densely pilose and becoming glabrous with
cluster,
dark
age. Sporocarps are variable in size, elliptic in dorsiventral cross-section,
brown almost and both teeth are very prominent.
to black,
Marsilea minuta distinguished from other closely related species of the
is
and
morphology pedicels sporocarps.
genus Botswana by of
in primarily the its
from non-
Pedicels M. minuta branched, separating eight other
in are it
minuta has 2-4 sporo-
branched Botswana. Marsilea also
species ocurring in
from M. apposita Launert
carps per cluster with prominent teeth, separating it
and M. ephippiocarpa Alston (3-10 sporocarps per clus-
(inferior tooth absent)
ter).
PRE)
In Botswana, M. minuta has been collected on Xhere Island [Smith 652,
Okavango
and the Thaoge River [Smith 1525, PRE) in the Delta. It is generally
Mozambique, Zambia, Malawi, Angola,
distributed Natal South Africa,
in
VOLUME NUMBER
AMERICAN FERN JOURNAL:
87
^
ely thank R. Glen, L. Fish, and M. Koekemoer for the u
South and thank
Pretoria, Africa, also
f S
Botswana. V
!rbarium the University of
at
USDA, USA,
review
Philadelphia, for oj
!
Literature Cited
Burrows, E. 1990. Southern African ferns and fern allies. Frandsen Publishers, Sandton, Re-
J.
South
public of Africa.
W. The and southern Butterworth's, Durban/
Jacobsen, B. G. 1983. ferns ferns allies of Africa.
Republic South
Pretoria, of Africa.
AB Maps
Parson, Q. N. 1993. The Botswana social studies atlas. Liber Kartor and International
AB, Stockholm, Sweden.
SCHELPE, E. A. C. L. E. 1970. Pteridophyta. Flora Zambeziaca (A. W. Exell and E. Launert, eds.).
Crown
London.
Agents,
ScHELPE, A. and N. C Anthony. 1986. Pteridophyta. Flora southern Africa (O. A.
E. C. L. E., of
Resean
Leistner, Botanical
ed.).