[pbs] Another "not really a bulb", but a geophyte
Joe Shaw
jshaw at opuntiads.com
Sat Sep 2 21:32:02 EDT 2006
Hi Gang,
Many Eucalyptus species, and some related plants, make a lignotuber. I'm
not sure what a lignotuber is anatomically, but I think it is some sort of
stem-perhaps like a potato storage organ.
Lignoubers allow Eucalyptus species (and Corymbia species, which used to be
classified as Eucalyptus) to regrow after fire or other damage. The
lignotuber is a tough storage organ, and because it is underground can allow
some species to survive 1 or 2 zones of colder temperatures than they might
prefer. I've had good luck with Eucalyptus citriodora (Corymbia
citriodora), the lemon scented plant. In the wild the tree can reach 60-100
ft-tall. In my garden growth is more modest.
However, the benefit of a lignotuber is that (at least some) eucalypts can
behave as dieback perennials in areas that are much too cold to allow tall
tree growth.
Many mallees, some trees, and some odds-and-ends species will perform well
in climates that are too cold to allow a "real" tree or shrub to develop.
The plants freeze back each winter and sprout stems that can reach 6-8
feet-tall each growing season. The benefit is especially nice with plants
that make beautiful foliage or which have strong and acceptable scents. I
do enjoy E. citriodora, a sprig can perfume a room with a pleasant lemony
scent.
One other Eucalyptus that I grow is E. viridis. This plant does well here
and, so far, has not suffered from root diseases that plague other eucalypts
I have tried to grow. E. viridis is a modest appearing plant, but has
wonderfully fragrant leaves that provide oils that are used in soaps and
cough drops, etc.
The main thing is that, for me, I treat these plants as bulbous-growing
things. If/when temperatures threaten to go very low, I mulch the plants
heavily, and let to tops freeze. In the spring, with warmth and some water
(warmth is key), the plants return and make a garden into a better place,
pleasing the nose as well as the eye.
NOTE: I've tried various eucalypts here in the greater Houston, TX area.
Many survive the climate and thrive for 2-3 years only to succumb to root
diseases. I've had some luck growing the plants from seeds in sterile soils
(microwave baked) and letting them get large before planting out-then I give
them the best drainage I possibly can.
TWO WINNERS (SO FAR):
1. Eucalyptus citriodora
2. E. viridis
I hope to try more mallee types in the future (shrubby or with many stems
from the base, not trees but 10-30 ft-tall).
LINK: Australia Plants, source of many seeds and some seedlings
http://www.australiaplants.com/
NOTE: Eucalypts can grow 4-8 feet in a year, even from seed.
LINK: The Hardy Euclalyptus Page
http://www.angelfire.com/bc/eucalyptus/
LINK: Eucalyptus camaldulensis, a lignotuber seems optional in this species
http://www.publish.csiro.au/paper/BT9830283.htm
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