Signboard on the 'Rooted in Time' self-drive tour of the Knysna forests in the Garden Route National Park. https://www.sanparks.org/parks/garden_route/

1. 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

2. As much as 10% 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.