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By Louwrens Opperman & Roy Vail


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Louwrens

Roy

 

Growing ferns from spore the easy way.

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The back ground images were sketched by my farther, Gert Opperman

 

By Roy Vail

A story is told, which may be true, that a wise professor instructed his student to carefully observe a fish and report back what he had seen.

Repeatedly the professor sent the student back to observe the fish more carefully.  After recording many details, the student noted a pattern in the fish.

He reported to his professor that the fish was bilaterally symmetrical.  The professor was pleased.  Those of us who are Platycerium hobbyists are also student observers.  We see many details of our plants.  I think that Platycerium, like the fish, show patterns and that once we see these patterns we will better understand our plants.

Shield fronds.


It is my opinion that the shapes of the shield fronds of Platycerium show adaptations to the environments where each species lives. Once we begin to notice and understand these, we can better take care of our plants.

Fundamental differences in the shield fronds of Platycerium are found in the shape they take above the bud. In some species they extend forward, leaving the top of the plant open. In other species they extend back toward the tree leaving the top of the plant closed.

I feel that shield fronds that extend forward is an adaptation by a species
to living in a dry environment, where a shape that collects water from
above, is an advantage. Shield fronds that grow back causing the top of the
plant to be closed is an adaptation by a species to living in a wet
environment where a shape that collects water could be a disadvantage.

The solitary Australian Platycerium superbum is an example of a species with
fronds that grow forward, forming an open top which functions in collecting
moisture, an adaptation to the dry forests where it lives.

The solitary Platycerium ridleyii, native to Borneo, is an example of a
species with shield fronds that grow back towards the tree, closing its top
to collecting moisture.  This is an adaptation to conditions high in the
trees of the tropical rain forest, where it lives. The natural habitat of
those two species is well known.

However the natural habitat of Platycerium ellisii and the mainland Africa
form of Platycerium alcicorne, commonly called Platycerium vassei, are not
well known. Since their shield fronds grow back closing the top of the plant
to collecting moisture, we can conclude that they are adapted to an
environment with abundant moisture and treat them accordingly.

In pup forming species the shape of the shield fronds determines the form
the mature cluster will take. I propose there are three basic forms.

1-The Ball:

A pup forming species, adapted to a moist environment by having shields that
grow back toward the tree, closing the top of the cluster to rain, matures
into a cluster shaped like a ball. Examples of this are: Platycerium hillii,
P. alcicorne, P. madagascariense and P. ellisii.

2-The Basket:

A pup forming species, adapted to a dryer environment by having shields that
grow forward, leaving the top of the cluster open to rain, matures into a
cluster shaped like a basket. Examples of this are: P. bifurcatum, P.
stemaria, P. willinckii var. venosa (the Mt. Lewis Platycerium) and P.
veitchii.
The basket is essentially a water storage vessel formed by a community of
individuals. Species that form baskets produce new pups in the wettest spots
in the cluster. These spots tend to be where the basket is leaking water.
The new pups function to better seal the basket.

Platycerium veitchii, the semi-desert pup forming Australian species that
lives on exposed bare rock, generally sandstone, is a very unique species.
The rock substrate prevents it from forming a full basket, instead it forms
a half basket on the face of rocks. Even so, the community as a whole is a
water storage vessel.

In the field it seems natural to collect a pup from the bottom of such a
cluster, but doing so may cause a leak in the vessel large enough to allow
the water supply for the whole cluster to drain away. If you must collect,
take a plant from the top.

Platycerium hillii, Platycerium bifurcatum and Platycerium veitchii are
pup.forming species native to Australia. They live in tropical rain forests,
tropical dry forests, and tropical semi-deserts respectively.
Platycerium hillii has shields that grow back toward the tree and have
rounded top edges, one extreme. Platycerium bifurcatum has shields that grow
outward and have top edges with points, the middle of the road.

Platycerium veitchii has shields that grow outward and have top edges with
long very thin points, the opposite extreme. Platycerium veitchii could not
spend the energy it takes to make the tall tips on its shields if it did not
receive some payback. I think the payback will be shown to be that dew drops
collect on the tall tips and run downward providing part of the water the
fern must have to survive in the semi-desert.

3-The Ring:

All pup forming species that remain, except one, grow into large
individuals.

Platycerium coronarium is unique among them in producing pups by rhizome
branching
. These branches grow along nearly the same plane as the original rhizome
resulting in a cluster, that when mature, becomes a ring around the tree.
The ring cluster is probably an adaptation to the large size of the
individuals in it.

Such large individuals would shade out pups that are not in the plane of the
original plant. Why Platycerium coronarium needs to form such large
individuals is unknown.

I have studied Platycerium andinum during three trips to Tarapoto, Peru, its
lectotype. It has large individuals and also forms rings, but its pups are
not produced by rhizome branching. Hobbyists have noticed that Platycerium
andinum tends to produce its pups on the sides.

Habitat photos in Hennipman and Roos, and other sources, show that
Platycerium elephantotis and Platycerium willinckii form rings.

However habitat photos also in Hennipman and Roos show that the small
Platycerium quadridichotomum also forms rings, a contradiction to my idea
that rings are an adaptation to the individuals in them being large.

Platycerium quadridichotomum is a rare, unusual and difficult Platycerium
which needs more study, but will probably not get it.

Barbara Joe Hoshizaki in 1972 concluded that Platycerium andinum is most
closely related to Platycerium quadridichotomum. Other writers have
commented that Platycerium andinum looks like a giant version of Platycerium
quadridichotomum. Perhaps ring formation is a trait in their line of
development .

-When it all gets confused-

The clear development of a cluster into a ball, basket or ring, can be
blurred by the shape of the tree the cluster is on and where the original
spore germinated. If the spore of a ring forming species germinates on a
large tree limb growing horizontally, only a partial ring can form. If the
limb is growing at an angle and several spores germinate one above the
other, the resulting partial rings above partial rings may look more like a
wreck than a pattern.

Balls, baskets and rings develop best on tree limbs that are vertical, but
even then, one basket above another, above another, above another, can
become one solid dazzling mass.

-What the hobbyist should do-

It would change the direction of growing Platycerium as a hobby if one of
our objectives became to have the cluster forming Platycerium look like they
do in the wild. Most of us do not have space for a mature Platycerium
bifurcatum basket, but if we use one of the small cultivars of Platycerium
bifurcatum, like Ziesenhenne or Newbill, a smaller version of basket is
possible on a hanging post.

Platycerium veitchii, if not placed on a rock, should be grown on a plaque
large enough for it to form a half basket.

The ball forming species will form half of a ball on a plaque, but a mature
ball covering a mass of moss hanging from a chain looks much more impressive
and natural.

The ring is nearly impossible for the hobbyist who must move plants inside
for the winter, however there is a solution. I have a group of mature
individual Platycerium andinum that are mounted on tall slider plaques.

During the summer they hang side by side with their buds all at the same
level so they form a ring around a centre post. They make a wonderful centre
piece in my fern grotto.

I feel that the judges of fern shows should be made aware of the forms the
species of Platycerium take in the wild and that hobbyists who succeed in
duplicating those forms should be given extra credit.

We need far more photographs of Platycerium in the field, particularly those
from Africa, Madagascar, the Seychelles and other islands. Hopefully this
situation will improve due to today's digital cameras and the ease of
sending photos by e-mail.

Like the student observing the fish without noticing its bilateral symmetry,
it was only after twenty years of growing Platycerium as a hobby, one trip
to Australia, and two trips to Peru, that, during the THIRD trip to Peru, it
dawned on me that Platycerium andinum was forming rings. Also like bilateral
symmetry, once noticed, it becomes obvious.

Comments are welcome.
vailroy@hotmail.com

Literature cited: Hennipman, E. and M. C. Roos. 1982. A Monograph of the
Fern Genus Platycerium (POLYPODIACEAE) Amsterdam: North-Holland Publishing
Company

Hoshizaki, B. J. 1972, Morphology and phylogeny of Platycerium species.
Biotropica 4:93-117

 

 

 

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