9/22/2014 2:25 PM
Purshia tridentata,
Antelope bitterbrush, buckbrush, quinine brush; Roseaceae family [lots of
shrubs are called ‘buckbrush’]
Native
Shrub
Once again I have very few photos and I do not have good
coverage.
The sources agree that blossoming is brief. Grant Cummings
and some sources say it has a powerful and pleasant odor when in bloom.
I call the northwest corner of Drumheller Springs
Park
There are two P. tridentata plants in Import Corner, one
large and one rather small.
010
020
The Purshia genus is named for F. T. Pursh who originally
described P. tridentata.
Tridentata, tri- 3, dent- teeth, refers to the three lobes
at the apex of the leaves. The tall sagebrush nearby is Artemisia tridentata
with similar but smaller thinner three lobed leaves.
Leaves
The flowers and leaves both rise from short ‘spurs’ off the
main stem, the leaves behind the flower. Slichter says the leaves are
alternate. [The alternate leaf pattern has only one leaf to a node, the nodes
separated by an internode. [Internode – a region of the stem between nodes
[growth points]]. The opposite pattern has two ‘opposing’ leaves at each node.]
This photo doesn’t seem to show any room for an internode on the spurs.
Jepson says the leaves of the genus are ‘+/- clustered on
short-shoots’.
030
Jepson Herbarium UC says the leaf ‘bases persistent,
overlapping, sheathing stem. Perhaps pulling the leaves off the spur would
reveal very, very short internodes. But I don’t think so.
Another task for observation next year.
040
045
047
Jepson says the leaves are ‘persistent or drought
deciduous’. I’ll see if the leaves remain over winter. But I suppose winter,
here, is a period of drought. I’m not positive but I think these plants lose
their leaves.
They are wedge shaped with three rounded teeth at the tip.
They are green with short hair on top, gray woolly
underneath. The Forest Service says, “Bitterbrush is well adapted to desert
life: with water-loss resistant leaves and long taproots …”
Slichter says the leaf margins ‘may be rolled under.’ Jepson
Herbarium UC says they are ‘strongly rolled
under’.
Jepson says the genus has ‘+/- sunken glands adaxially’. I
need a translator. And a microscope. [Adaxial – facing toward the stem of a
plant (especially denoting the upper surface of a leaf). There are more
complicated definitions.] There is something sticking up at the base of the
leaf in the photo. I think it is damage, not a gland.
The leaves don’t look very appetizing but several sources
call them important to browsing wildlife and cattle. Utah extension says the leaves taste bitter.
The Forest Service says the leaves are thick. There is no
indication of that in these photos.
Jepson says leaves of this species have a spiny tip. No
spiny tip shows on this leaf.
050
Perhaps the dark green rim indicates margins ‘rolled under’.
It doesn’t indicate that they are ‘strongly’ rolled under.
060
Inflorescence
The inflorescence is a single flower on a short woody stem
above a cluster of leaves.
The flower has 5 petals, smooth and somewhat irregular in
the photo below. It has a 5 lobed calyx [or hypanthium], the lobes in the photo
are quite regular and somewhat hairy.
The petals are often characterized as yellow, sometimes as
white. One source said they look yellow because of the abundance of yellow
pollen.
The petals apparently fall away quickly, perhaps as an
aspect of their water conservation strategy. They are said to be in bloom
briefly.
070
Calyx or hypanthium? Who is the best authority?
Burke Herbarium UW:
Calyx with stalked glands and wooly hairs, tube funnel
shaped, 5 lobes, entire.
Paul Slichter:
5 lobed calyx
Jepson Herbarium UC Berkeley, of the genus Purshia
Hypanthium ± funnel-shaped, outside hairy,
partly glandular or not,
bractlets small, lanceolate.
Jepson, of the species P. tridentata:
Hypanthium +/- 2.5-5 mm
calyces bell-shaped, woolly- or cobwebby-hairy
and stalked-glandular, 5-lobed, the lobes oblong-egg-shaped, 3-4 mm long;
[Oh! An hypanthium is characteristic of plants in the Roseaceae
family and P. tridentata is in the Roseaceae family. Even so the funnel doesn’t
fit the definition of an hypanthium very well. It looks a lot like the fused
sepals of a calyx.]
The stalked glands are displayed in the photo below. The
shape of the calyx/hypanthium is not bell shaped.
080
Sources say there are 25 stamen. I can’t count that many in
any of my photos but there are a lot.
090
There is a single pistil.
100
It looks like the whole style is covered with pollen.
110
Root
Purshia tridentata sometimes has the nodules to fix nitrogen
but, it seems, doesn’t do it very well.
The taproot can reach 15 to 18 feet. It has few shallow
roots.
Fruit
The paper thin covering of the seeds rots over winter and
seeds germinate in the spring, only if there is normal or above normal spring
rain.
It propagates by seeds. It also propagates by ‘layering’.
Layering occurs when branches touch the ground and develop roots that become
new plants.
It reaches seed bearing age in 8 to 10 years.
Rodents and ants may stash the entire crop of seeds. Uneaten
seeds are a key source of new plants.
Rodents like to eat millet. They like P. tridentata seeds
better. The seeds taste bitter.
Miscellaneous notes
Purshia tridentata can be long lived. One plant was found to
be 128 years old, 12 feet high and 20 feet across.
It is pollinated by insects. It can be wind pollinated. It
does not self-pollinate.
Competition with cheat grass inhibits reproduction of P. tridentata.
A purplish dye was made from part of the seed.
“Bitterbrush is important browse for cattle,
sheep, and goats, especially in late fall and winter when the ground is
snow-covered. It is usually not eaten by horses.
It is excellent browse for many species of wildlife, and can be critical winter
browse for deer.”
The leaves taste bitter.
Some Graphics Play
120
130
No comments:
Post a Comment