Castilleja - the Paintbrush
genus
By Bruce Homer-Smith
Paintbrushes are
colorful, attracting our eyes and those of pollinators. Flowers are often hidden under colorful,
leafy bracts. Here are some examples:
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Colorful bracts
cover most of the tubular flowers:
Common Paintbrush (Castilleja affinis) |
Common Paintbrush (Castilleja affinis) Drawing © John Muir Laws |
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Woolly Paintbrush
(Castilleja foliolosa) |
Wight’s
Paintbrush (Castilleja wightii) |
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Behind
the bracts, all paintbrush flowers have three parts in common –
a tube with nectar at the bottom, and –
two petal structures at the top of the
tube - a lip and a beak (aka galea). The length of the tube,
relative to the beak, varies between species.
Also, the size of the lower lip can vary - tiny (less than 1/10”) as in
the case of Common Paintbrush, or quite developed, as in Cream Sacs and Owl’s
Clover.
Common Paintbrush (C. affinis), Giant Paintbrush (C. miniata) and Owl’s Clover (C. exserta) Drawings © John Muir Laws |
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Cream
Sacs uses an inflated flower lip to attract pollinators
Cream Sacs (Castilleja
rubicondula) |
Owls Clovers show
large, decorated lips at the top of the floral tube.
Graceful Owl’s Clover (Castilleja
densiflora ssp. gracilis) |
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Paintbrushes
are hemi-parasitic – tapping roots of adjacent plants for water and
nutrients. Desert Paintbrush (Castilleja linariiflora) |
This means you’ll
often find them scattered among other flowers and grasses.
Lemmon’s
Paintbrush (Castilleja lemmonii) |
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Hummingbirds, butterflies
and bees reach down the long floral tube to get nectar.
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Distribution
Paintbrush is
widespread, from deserts to alpine meadows, with about 200 species worldwide,
concentrated in western North America. Paintbrushes
can thrive in tough situations (lack of water, poor soil or short growing
season) by tapping into the roots of adjacent grasses and flowers.
Paintbrush – a
hemi-parasite
Paintbrush is a
hemi-parasite because it uses both photosynthesis and taps into the roots of
adjacent plants to gain carbohydrates.
Paintbrush uses haustoria on its roots to
penetrate the cell walls of adjacent plant roots. The haustoria sit between the cell wall and the
cell membrane of the host plant’s vascular bundles, absorbing water,
carbohydrates and nutrients.
Ecological impact
Paintbrush’s ability
to parasitize adjacent plants impacts the many ecosystems where it is
found.
·
It
can change the competitive balance - for instance, paintbrush can break up a
monoculture by sapping the dominant species, making room for other plants and
animals to be successful.
·
There
may be subtle benefits to the host plant – for instance, the interplant
connections may enhance communication in response to insect invasions of the
community.
For more, see https://oleaeuropea.wordpress.com/2011/07/27/indian-paintbrush-a-pretty-parasite/
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Corrections/Comments:
bruce@PlantID.net Copyright:
https://PlantID.net/Contributors.aspx |
