8 Rooted in Time: Dal van Varings

8 Rooted in Time: Dal van Varings

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  The ferns -about 12,000 species in all - reproduce asexually via spores which are usually carried on the undersides of their leaves. They produce neither seeds nor flowers. Their leaves usually emerge as characteristic ‘fiddleheads,’ which expand into delicately divided fronds. Although the ferns are often considered amongst the oldest of the vascular plants (they first appear in the fossil record 360 million years ago) many of the families which we know today began to emerge only about 145 million years ago - after the flowering plants began to dominate. Although ferns don’t feature much in the world’s economy, one species is economically important in the Knysna forests: the florists fern, or seven weeks fern (Rumohra adiantiformis). SEVEN-WEEKSFERN (Florist’sfern;Knysnafern; Seweweeksvaring) Rumohraadiantiformis Around the world, various species of fern appear in art, mythology, and traditional medicine; are gathered for food; are grown as ornamental plants; and are planted for the remediation of contaminated soils. They’re great filters of the air, so they’re effective in help- ing to prevent sick building syndrome, and research from NASA indicates that they may be useful for cleaning the air in space stations. The fern denotes endurance and resourcefulness in the Ghanaian system of writing known as the Adinkra symbols: “An individual who wears this symbol suggests that he has endured many diversities and outlasted much difficulty.” (The Adinkra Dictionary: A Visual Primer on the anguage of Adinkra by W. Bruce Willis). And the Victorians - of course - viewed them as signs of middle-class respectability, and grew them wherever they could: indoors, outdoors, in hanging baskets, on fern stands, in glazed boxes called Ward cases, and in ornate ferneries. They collected, swapped, bought and sold ferns - and they even had a term for their obsession: ‘pteridoma- nia’ (a pteridophyte is a vascular plant that reproduces by spores). The word was coined by the clergyman and naturalist Charles Kingsley - a passionate advocate of better science education for young people. "Your daughters, perhaps, have been seized with the prevailing 'Pteridomania' and are collecting and buying ferns, with Ward's cases wherein to keep them (for which you have to pay), and wrangling over unpronounceable names of species (which seem different in each new Fern-book that they buy), till the Pteridomania seems to be somewhat of a bore: and yet you cannot deny that they find enjoyment in it, and are more active, more cheerful, more self-forgetful over it, than they would have been over novels and gossip, crochet and Berlin-wool." (Charles Kingsley: ‘Glaucus; or, the Wonders of the Shore,’ published 1855). abitaboutferns SIGNSOF RESPECTABILITY Ferns prefer damp, sheltered places - which is why they make up one of the biggest groups of plants in the understory of the forests. Although they’re found in many of the temperate rain-forests in other countries, seven-weeks ferns from the Knysna forests seem to be the favourite of florists from around the world. The rich, moist, well-drained conditions in which they grow here ensure that our ferns reach optimum size and luxuriance. KNYSNA'SFERNINDUSTRY The name should be the give-away: the seven-weeks fern lasts for remarkably long periods in the vase - which is why it became so popular with florists in the 1970s. By the 1980s, private contractors were receiving permits to harvest the seven-weeks fern from the Knysna forests - but a lucrative black market quickly arose, and illegal pickers began invading the forests at night (although better oversight eventually brought the problem under control). At first, the pickers left the ferns to rest for as little as five- to twenty five weeks between harvests - but quality and quantity quickly decreased. Careful research showed, though, that the leaves of these ferns grow most rigorously between September and November, and that that they remain vigorous for up to two years. The harvesting cycle was therefore increased to 12-, and then to 15 months, and the problem was solved. valleyofferns
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  As much as10% of the total area of these forests has been infested by alien species - plants which have been introduced for various reasons (for farming, for the stabilisa- tion of sand dunes, as ornamentals), but which have no natu- ral enemies in this eco-system - which allows them quickly and aggressively to invade and dominate areas in which they take hold. Aliens cause natural watercourses to dry up, increase the risk and potential damage of bush fires, reduce biodiversity, ALIENPLANTS Seven weeks-ferns reach a height of about one metre. They’re easily grown in shady- to semi-shady positions in well-drained, loamy soil that’s constantly moist, but not waterlogged. They like strong, but indirect light - plant them in the dappled shade of an evergreen tree or under 80% shade netting - and high humidity (which is why they dislike wind: it reduces the humidity around the leaves, which increases transpiration, which causes the fronds to become scorched). They’re hardy to light frost. Seven-weeks ferns are available from most nurseries and garden centres in the Garden Route. It’s illegal to remove them from the forests. SWORDFERN (PinkleafBlechnum) Blechnumpunctulatum The blechnums are the dominant ferns of these forests - particularly Blechnum punctulatum (the sword fern), and B. capense (the Cape deer fern). The sword fern grows in light- to full shade both in drier parts of the forests, and in relatively wet positions (alongside mountain streams, for example). It reaches a height of about 500 mm, although individual fronds usually grow to between 220 and 270 mm in length. The leaves are glossy, long, and feathery, and young leaves are noticeably pink in colour. Sword ferns are commercially harvested for the cut-flower market - and they were a favourite of Victorian-era botanical artists (who knew them as ‘Lomaria punctulata’). CULTIVATION CAPETREEFERNBosboomvaring;Cyatheacapensis The indigenous Cape tree fern bears a crown of lacy fronds on a slender trunk, and grows to a height of about 2.5 m. It’s usually found in colonies on moist ground, often close to forest streams. It’s propagated from spores, but it doesn’t take easily to transplanting, so it’s not a hugely popular garden specimen. retard the rejuvenation of disturbed areas, and cause many other, similar problems for natural systems. Their management and eradication is of vital concern for the long-term health of ecosystems wherever they’re found. Here are some of the invasive aliens of concern in these forests: Bugweed(Solanummauritianium) A large shrub or small tree that was introduced as an ornamental. It grows to between 2- and 4-metres in height. Most parts are covered with white, velvety hairs. It has dull green, velvety leaves, purple flowers, and yellow, berry-like fruit (which are poisonous). Bugweeds are controlled by removal, and with herbicides. A ‘bugweed lace bug’ (Gargaphia decoris) has been introduced to various parts of South Africa as a biological control agent. Blackwattle(Acaciamearnsii) This is perhaps one of South Africa’s most troublesome invaders: it poses a particular problem to water courses. It’s a medium-to large-sized tree with feathery, dull- to dark-green compound leaves; it bears huge trusses of yellow, pompom-shaped flowers followed by brown, woody seedpods. It was originally introduced to create windbreaks - because it grows so quickly - but it has many other uses (it produces tannin for tanning, it’s used for pulp, etc.), and it is still planted commercially in some parts of the country. It is now controlled by ring-barking, and with herbicides. Various biological agents - weevils, midges, and even a fungus - have been introduced to South Africa in an attempt to slow the black wattle’s speed of reproduction. Australianblackwood-Australiese swarthout(Acaciamelanoxylon) Originally planted in exploited parts of the Knysna forests at the beginning of the 20th Century for its very popular and valuable timber. It grows to a maximum of 20 metres in height, and bears sprays of pompom-like flowers in spring. While not as much of a problem as A. mearnsii, it nevertheless provides a measure of threat to the forests. It’s controlled by removal, and with herbicides.