Re: Echium vulgare and other invasives in California
- Subject: Re: Echium vulgare and other invasives in California
- From: d* f*
- Date: Thu, 16 May 2002 11:44:44 -0700 (PDT)
It certainly never hurts to know what plants are
invasive in other parts of the world, but as Joe says,
that doesn't necessarily mean that they will be
invasive everywhere. Lantana camara seems to be much
more of a problem where there is summer rainfall, as
in Hawaii and south Florida, where it is an invasive
pest. Our extraordinarily long dry season seems to
limit this one getting established from bird spread
seed here in California.
When I was growing Echium vulgare in my own garden, it
was quite well behaved and non invasive. Invasive
plants in irrigated gardens here would have to include
Pittosporum undulatum, Cotoneaster lacteus, Eriobotrya
japonica, Hedera canariensis, Juglans nigra, Rubus
discolor/Himalayan blackberry, and Oxalis pes capri
among others. Invasives in non irrigated
areas/native habitats are a whole other list, and well
addressed in the lists of invasives published by the
State of California and the Federal Government.
I tend to be most cauxious with plants that set viable
seed/berries which are attractive to birds, and
readily self sow in our climate. As I am in a dense
urban neighborhood, I am less concerned about things
like Impatiens balfourii getting into the wild, which
it is fully capable of doing if I lived next to a
creek where it could spread quite easily. I also grow
Senecio tamoides, which sets abundant seed, and is
similar in appearance to Senecio milkanioides. S.
tamoides has given me no indication of being invasive
except that it can root adventitiously along stems in
contact with the ground, and could engulf my house if
I let it, but hasn't shown any signs of self sowing in
the garden, or invading the neighbors. Oenothera
berlandieri is certainly another invasive garden thug,
but not inclined to spread beyond irrigated gardens
here, as it doesn't seem to set seed or survive
without summer water.
The various Pennisetums can also be problematic, with
P. clandestinum/Kikuyu grass well established all
along the coast highway and P. villosum equally well
established along railroad tracks. P. setaceum is a
rampant weed along highways and disturbed road
embankments throughout Southern California, similar to
Cotaderia jubata all along the coast on disturbed
slopes.
Some other Southern Hemisphere plants that are locally
found as invasives include Zantedeschia aethiopica in
coastal creeks, and Chasmanthe aethiopica in the
vicinity of abandoned gardens. There are certainly a
plethora of South African bulbs which easily spread
around the garden, but don't seem to be a problem in
the wild, such as Crocosmia, Lapeirousea laxa, Homeria
collina, and the Argentinian Ipehion uniflorum.
Ubiquitous weeds in California urban areas would have
to include Foeniculum vulgare, and many of the
European annual grasses.
This is my short list of things to be avoided based on
my local experience in the San Francisco Bay Area of
California.
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