Indigenous plants

An indigenous plant or animal is one which occurs naturally in the place in which it is currently found, and has not been assisted in its travels by people. Being indigenous does not mean that a species has always occurred where it is now found - some species shift their distribution quite quickly, for example, when blown by strong winds or transported naturally by ocean currents. The indigenous concept also applies to habitats, and does not refer only to a geographical area. For example, birds indigenous to dry thomveld are very different from the birds indigenous to mistbelt forest, even though they may be only 10 km apart. An endemic species is not only indigenous, but is restricted to a particular area. The blue crane, for example, is indigenous to southern Africa, and is found nowhere else. This makes it endemic. The wattled crane is also indigenous, but it is not endemic to southern Africa as it is also found further north in Africa.

Alien plants

A species which does not occur naturally in a Country (i.e. is not indigenous), but which has been introduced there by people, is called an alien. Sometimes people use the word "exotic" but this is not the best word as it has many other meanings. A few alien species reproduce and spread, unassisted by man, into areas where they are not wanted - these Invasive aliens pose a serious threat to nature conservation. Expensive and drastic measures are required to control invaders. Some indigenous species also invade new areas but these invasions are brought about by changes in the area Invaded, e.g. Acacia karoo rapidly takes over overgrazed grassland. Control of such invasions involves correcting the management of the area, in addition to control of the invading species.

Horticulture in the Botanical Garden

Horticulture is "The art of gardening" or as it is becoming nowadays, "the science of gardening". What has been done in the Garden Route Botanical Garden is more art than science! Attempting to grow only indigenous plants from the Southern Cape as we do is a real challenge. There a several very basic factors with a bearing on any subsequent horticultural handling, that have to be understood first. Ideally the natural habitat and climate for each plant or group of plants should be recreated as far as possible

Habitat and climate are influenced by many factors:

• a) Gradient- flat or sloping, steep, gentle etc? very important for^ur plants as so many of our plants grow on a slope and therefore need good drainage
• b) Aspect which direction does the slope face? North & West slopes are generally dryer and hotter with full sun ;is vegetation is sparse. South & East slopes are cooler and wetter with plants otten in shade or at least roots well shaded as vegetation is dense.
• d) Rainfall winter or summer, how much in a year? If rain falls in winter it means the plant can handle cold and wet at the same time (but often die if hot and wet at the same time, if in summer plants can stand heat and \vcl together (but may die if cold and wet'). This is much more important than people realise.
• e) Soil sandy, loam. clay. rocky, deep or shallow etc? this not only has a bearing on how much fertility the plant needs or gets but also on how quickly the soil drains, how long it retains moisture, and how hot or cool it gets.

Dry Fynbos from North & West slopes - needs infertile soil. slightly acid. extremely well drained and never remaining wet more than a day or so (steep slopes with clay or better still gravelly shaley soil on a slope), tolerate cold and wet but never wet in full hot sunshine (water only in evening or on grey days), has very sensitive surface roots because grows in shallow soils (never cultivate or disturb around roots as damage leads to death!)

Coastal fynbos -It varies hugely from dense high fynbos like the Knysna Hornlee area to windblown and bonsaied scrubby fynbos as on cliff tops at Ballot's Bay and Herold's Bay to limestone fynbos as at Gouritz & Stilbay. Soil is often rocky, shallow. with very little loam. Coastal plants need sandy soils, very well drained, and depending on natural position on dunes etc need shade or full sun. Sand is more fertile than leached mountain sides, but mulch on top is better than digging in compost or manure. Notice that most dune plants grow on slopes, flat areas are often bare! Plateau vegetation, scrub and shrubby bush contains important decorative elements such as Watsonias. Pteronias. Phylicas. Metalasia. Helichrysum. some Ericas. Sandy or clay soil, often neutral or slightly acid.

Little Karoo, Succulent Karoo, Nama Karoo, Renosterveld - soils are much more fertile than the fynbos areas but much drier and hotter in summer and colder in winter! It grows naturally on fairly flat areas but not together with high rainfall, so one has to ensure good drainage by planting on a slope or a mound of gravel and sandy soil and facing North or West to gain heat. Many daisies, bulbs, aromatic small colourful shrubs such as Hermannia etc. grow here. Many are useful in bedding and to give colour and grey foliage, but often difficult to mix with fynbos species without a lot of clever manipulation of the conditions in the garden.

Wetland - although the GRBG wetland was originally manmade. it effectively functions now as a natural system and as such is a very valuable educational tool. It is very obvious how different the vegetation is in a line starting with the high water mark of the underground water table and again with the high water mark of the actual surface water areas. Water is a really vital element in South .African ecology and the environment and should be stressed as such.