Thesis (PhD)--Stellenbosch University, 1994. / ENGLISH ABSTRACT: Fifty nine species were studied in this taxonomic treatment of section Hoarea
(Sweet) DC. of the genus Pelargonium L'Herit., which was last revised by
Knuth in 1912. The majority of species occur in the winter rainfall area of
the south-western Cape, but some species occur in the eastern Cape, a region
of winter and summer rainfall. A few species also occur in the summer
rainfall area in the central Karoo.
Morphological, leaf anatomical, palynological and geographical data were
studied in order to delimit the taxa and to determine their relationships. Eight
new species were described and several name changes were made. Diagnostic
features of the section are the regularly or turnip-shaped tubers with numerous
dark brown peeling tunics or periderms and apically a short flattened stem
from which the leaves and scape emerge. The zygomorphic flowers are
almost sessile, because the pedicels are very short (0,5--1 mm) and the
hypanthia long (6--100 mm). A large variation occurs in leaf form and floral
structure, and the section is divided in 14 different floral groups, mainly
based on the structure of the androecium and the tectum of the pollen grains,
although petal form and size are also considered in clustering the species.
Section Hoarea with its deciduous geophytes and sometimes extremely
zygomorphic flowers, exhibits advanced morphological characters. Because
of the large variation in the structure of the androecium, pollination biology
was probably one of the major driving forces in the evolution of the section,
and the annual rainfall plays an important role in the distribution patterns of
the different species. / AFRIKAANSE OPSOMMING: Neen en vyftig spesies is bestudeer in hierdie taksonomiese ondersoek van
seksie Hoarea (Sweet) DC. van die genus Pelargonium L'Herit., wat laas
deur Knuth (1912) hersien is. Die meerderheid van die spesies kom in die
winterreenstreek van die suidwes Kaap voor, maar sommige spesies word ook
in die Oos-Kaap, wat 'n winter- en somerreenstreek is, aangetref. Enkele
spesies kom in die somerreenstreek van die sentrale Karoo voor.
Morfologiese, blaaranatomiese, palinologiese en geografiese data is bestudeer
om die verskillende taksons af te baken, en terselfdertyd verwantskappe
tussen die onderskeie spesies te bepaal. Agt nuwe spesies is beskryf en
verskeie naamsveranderinge is gemaak. Diagnostiese kenmerke van die
seksie is die reelmatiggevormde of raapvormige wortelknol met verskeie
afskilferende donkerbruin periderms en apikaal 'n verkorte stingel waaruit
blare en 'n bloeispil groei. Die sigomorfe blomme is byna sittend, aangesien
die blomstele uiters kort is (0,5--1 mm) en die hipantiums relatief lank (6--
100 mm). 'n Groot variasie in blaarvorm en blomstruktuur kom voor, en die
seksie word in 14 verskillende blomvorms verdeel. Hierdie blomvorms is
hoofsaaklik gebaseer op die struktuur van die andresium en tektum van die
stuifmeelkorrels, alhoewel kroonblaarvorm en -grootte ook 'n rol gespeel het
in die onderverdeling van die seksie.
Seksie Hoarea met sy bladwisselende geofiete en soms uiters sigomorfe
blomme, vertoon gevorderde morfologiese kenmerke. Die groot variasie in
die struktuur van die andresium dui op 'n moontlike prominente rol wat die
bestuiwingsbiologie gespeel het in die evolusie van die seksie, en die jaarlikse
reenval speel 'n belangrike rol in die verspreidingspatrone van die
verskillende spesies.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/58560 |
| Date | 03 1900 |
| Creators | Marais, Elizabeth Maria, 1945- |
| Contributors | Van der Walt, J. J. A., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 369 pages : illustrations, maps |
| Rights | Stellenbosch University |
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