learning about biodiversity

Combretums or bushwillows are common and conspicuous trees and creepers of the African bushveld –

probably best known for the papery, winged fruits that most of them have. Well known among them are the Leadwood (Combretum imberbe) and the Flame Creeper (Combretum microphyllum). So it was exciting to hear that a new Combretum had been found in the depths of KwaZulu-Natal when an article describing the new species appeared in the South African Journal of Botany.

The new tree has been named Combretum stylesii, and is a rare species known only from a rugged, ten kilometre stretch of the Tugela River within the Maphumulo District Municipality to the north of Durban. It appears to have been hidden by its inaccessible habitat, although this is now being threatened by road development and rural sprawl.

The tree is named after David Styles, a member of BotSoc’s KZN Coastal Branch who has collected several thousand plant specimens in the province over the past decade, in the process discovering a number of other, smaller plant species. David is editor of the journal published jointly by BotSoc’s KZN Coastal Branch and the Durban Botanic Gardens Trust, PlantLife, and he is founder and administrator of the Yahoo! discussion group, Plant-chat.

David first noticed the tree in 2004 and immediately realized that it was an unknown species. However, both fruits and flowers were needed in order to complete its description, and it took four years to do this as the locality is remote and flowering brief and erratic. Many visits were made to the area, but in some years no flowers were found. Eventually enough material was collected and sent to Olivier Maurin, a PhD student at the University of Johannesburg, and Professor A.E. (Braam) van Wyk, the renowned plant taxonomist based at the University of Pretoria.

In addition to more obvious distinguishing features, bushwillow species can be told apart from each other by tiny scales on the leaves that are as unique as a human fingerprint. The scales of Combretum stylesii were studied under a microscope and its DNA was analyzed, proving that it was indeed a distinct species.

The Tugela Bushwillow grows as a small tree or as a vigorous strangler, climbing up and over other trees. The vegetation in which it

occurs is classified as Eastern Valley Bushveld and the area is arid and hot with temperatures often reaching over 40 degrees centigrade in the summer.

According to David, it is possible that this new Combretum may occur in other localities in the area, as vegetation along this part of the Tugela River is not well known. He believes that further exploration might result in other new discoveries being made.

Combretum stylesii grows easily from seed, and is currently being grown in Kirstenbosch National Botanical Garden.

The Tugela Bushwillow A new species of Combretum from KwaZulu-Natal

by Marilyn Bodasing

ABOVE LEFT: Combretum stylesii leaves. Photo: David Styles.ABOVE RIGHT: The Tugela Bushwillow (Combretum stylesii) growing as a free-standing tree. RIGHT: The habitat of the Tugela Bushwillow (Combretum stylesii) is dry valley bushveld along the Tugela River. BELOW: Combretum stylesii leaf and fruit.BOTTOM RIGHT: The Tugela Bushwillow (Combretum stylesii) strangling Euphorbia tirucalli. Photos: David Styles.

“My idea of education is to unsettle the minds of the young and inflame their intellects.” Robert Maynard Hutchins.

What’s the buzz?Veld & Flora updates teachers and scholars on what is happening in the world of science, especially the Life Sciences and Geography. Even if an article is not directly about teaching the National Curriculum Statement, it will widen your and your class’s general knowledge, and give you a step up the academic ladder.

A pollination syndrome You may have noticed that the flowers of different species sometimes look the same. This is because they are hoping to attract the same pollinator. This is called a pollination syndrome. Read about a pollination syndrome in the article ‘Klein Karoo buzz: Why unrelated flowers look the same’ by Jan Vlok in the March 2009 issue of Veld & Flora on page 24. It describes how four unrelated species look similar because the attract the same pollinator which is a long-tongued fly.

Plant a pollinator-friendly garden in your school Lists of suitable indigenous plants can be found in the book Cape Flats Flora Treasures: A teacher’s guide to Active Learning in Cape Town Schools and in Charles and Julie Botha’s books Bring Nature Back to your Garden and Bring Butterflies Back to your Garden. If you want to find out more about these books, contact the editor at veldfloraed@gmail.com.

QuizzzCan you guess what pollinates the plant below? Tritoniopsis nervosa has long-tubed, fragrant cream-coloured flowers that are pollinated by long-proboscid moths. A proboscis is an insect’s tongue, hollow in the middle for sucking.

Bee a show offSend a poster or study that your class has done on pollination to the Editor of Veld & Flora (see address on page 98) and bee in line to win a subscription to the Botancial Society of South Africa, which includes free copies of Veld & Flora for your school library.

What the new Life Sciences curriculum for Grade 12 says

STRAND: Life processes in plants and animals Grade 12: Responding to the environment and reproductionIn Grade 10 and Grade 11 some of the life processes that enable plants and animals to survive have been covered and related to organisms’ different and changing environments. Plants and animals have a variety of ways of detecting stimuli and responding to their environments. The way of life, for example, whether relatively stationary (plants) or mobile (most animals) influences this process greatly. Reproduction is the one life process that is not necessary for the survival of the individual but is concerned with continuation of the species

LO1 Investigating phenomena in the Life Sciences

LO2 Constructing Life Sciences knowledge

LO3 Applying Life Sciences in society

Flowers as reproductive structures

Observation of the ad-aptations of the flowers selected in LO 2.

Adaptations of flowers for differ-ent forms of pollination and dif-ferent pollinators: one example of a wind-pollinated flower, an insect-pollinated flower and a bird-pollinated flower (South African examples only).

Significance of the seed.

The importance of seeds as a food source.

The use of seed banks to main-tain biodiversity

Sexual reproduction

in plants.

FlowersA flower is the reproductive

organ of a plant. It contains the fe-male and male sex organs (the carpel or

pistil, and stamens) which are protected in-side the corolla (the petals). The calyx (sepals) protect the flower bud. Flower shape varies: proteas and daisies consist of a flowerhead

(inflorescence) of many simple flowers whereas others, like the gladiolus, is

a single flower on a stem.

PollinationThe transfer of ripe pollen

from the anthers to the receptive stigma is called pollination. Although

some plants are able to pollinate themselves (self-pollination), cross-

pollination between two different plants of the same species is better as it enhances

genetic diversity. As plants cannot move, they rely on pollination

agents like wind, water and animals to help.

FertilizationOnce the pollen grains reach the

stigma of the female flower, the grains grow down the style in order to reach the

ovules. When a pollen grain meets an ovule, they fuse and fertilization takes place. In other

words, the gametes (the ovule and pollen cells that contain the haploid number of

chromosomes) fuse to form a zygote that contains the diploid number of

chromosomes.

Seed and fruitAfter fertilization the ovule

(now a zygote) develops into a seed and the ovary becomes the fruit. A seed

is made up of an endosperm, which is the food store, and a seed coat (testa) which is the outer covering that protects the seed. Seeds are adapted for dispersal in many

different ways. Animals (including humans) rely on seed (like maize

and wheat) and fruit for survival.

Draw a mind map

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