Dissertation (PhD)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The previous revision of Zygophyllum L. by Van Huyssteen (1937) included all
known species of the cosmopolitan genus Zygophyllum. The present study deals
with the species of Zygophyllum occurring in the southern African region which
includes Angola, Namibia, Botswana and South Africa. The majority of Zygophyllum
species occur in the arid and semi-arid, western parts as well as in the interior parts
but some species do occur to the south of the area where milder climatic conditions
are experienced. Zygophyllum species are typically described as shrubs or
shrublets, rarely herbaceous annuals or biennials, with simple, sessile leaves or
sessile, bifoliolate or petiolate, bifoliolate leaves of a succulent texture.
Macromorphological as well as phytogeographical data were studied in order to
delimit the taxa and to determine their relationships as well as their distributions.
Various tables summarizing diagnostic characters of taxonomic importance as well
as line drawings depicting the salient features of the species are given.
The division of the genus Zygophyllum into two subgenera was investigated and this
division is corroborated with additional evidence concerning floral, fruit and seed
morphology. The absence or presence of an elaiosome on the seeds found in the
two subgenera reflects on their different dispersal strategies. The structure of the
morphologically different mucilage produced by the seeds of the two subgenera is
touched on. The division of the subgenera Agrophyllum (Neck.) End!. and
Zygophyllum, each into several sections, was investigated. Two sections, one from
each subgenus, were transferred: the monotypic § Morgsana (Huysst.) Van Zyl to
subgenus Zygophyllum; and the monotypic § Grandifolia Eng!. to subgenus
Agrophyllum. The § Prismatica Van Zyl is newly described and the §Annua Eng!. is
reinstated. seventeen new species are described, a few names sunk into synonymy
and several name changes made. / AFRIKAANSE OPSOMMING: Die vorige hersiening van Zygophyllum L., deur Van Huyssteen (1937), het alle
bekende spesies van die kosmopolitaanse genus Zygophyllum ingesluit. Die
huidige studie handel slegs oor die Suider afrikaanse Zygophyllum-spesies wat in
Angola, Namibië, Botswana en Suid-Afrika voorkom. Die meerderheid Zygophyllum
spesies groei in ariede en semi-ariede dele aan die weskus asook in die binneland
van die area maar sommige spesies groei ook in die suide van die gebied met 'n
meer gematigde klimaat. Zygophyllum-spesies word beskryf as struike of halfstuike,
is selde kruidagtige, een- of tweejariges en het gewoonlik eenvoudige, sittende blare
of sittende verdeelde of gesteelde verdeelde, sukkulente blare.
Makromorfologiese en geografiese data is bestudeer om die verskillende taxa af te
baken, om verwantskappe tussen die onderskeie spesies vas te stel sowel as om
die verspreiding vir elke takson aan te gee. Tabelle met die vernaamste
taksonomies kenmerke asook lynsketse van die mees belangrike kenmerke van die
verskillende species word verskaf.
Die verdeling van Zygophyllum in twee subgenera is ondersoek en is, met behulp
van bykomende blom-, vrug- en saadmorfologiese inligting, volkome regverdig
bevind. Die aan- of afwesigheid van elaiosome op sade dui op verskillende
saadverspreidings metodes. Die morfologies-verskillende slymlaag wat deur die
saad van die twee subgenera produseer word, is kortliks beskryf. Die verdeling van
die subgenera Agrophyllum en Zygophyllum in verskeie seksies is ondersoek. Die
monotipiese subseksie Morgsana word na subgenus Zygophyllum en die
monotipiese § Grandifolia na subgenus Agrophyllum verskuif. Die § Prismafica
word as nuut beskryf en die § Annua word in hergebruik geneem. Sestien nuwe
spesies word beskryf, enkele name word in sinonimie geplaas.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51628 |
| Date | 03 1900 |
| Creators | Van Zyl, Loretta |
| Contributors | Marais, E. M., 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 | 449 p. : ill. |
| Rights | Stellenbosch University |
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