The document summarizes a visit by the author and a friend to the Horse Rock Ridge Natural Research Area in the western Cascade Mountains of Oregon. Some key details: - The area is protected land that contains meadows and forests on 24 million year old basalt lava flows. It features unusual plant life adapted to the shallow, nutrient-poor soil. - During their early spring visit, they observed many wildflowers blanketing the meadows, including shooting star, paintbrush, and fairy slipper orchid. Smaller versions of larger plants thrive in the poor soil. - The area offers views of surrounding mountains and forests. Though some logging occurs nearby, over 80 acres of the meadow is preserved through

1. Horse Rock
Ridge
Research
Natural Area
Linda R. McMahan, Ph.D.
Retired, OSU Extension Service
Oregon State University
April 28, 2014

2. Perched on a mountain
at 2700 feet in the
western Cascade
Mountains, the area,
protected by the U.S.
Bureau of Land
Management since the
1980’s, provides a
stunning contrast to the
surrounding forests. My
friend Tim and I
revisited this
outstanding natural
place early in the year
to view spring flora. Paintbrush, Castilleja hispida, partially
parasitic on surrounding vegetation.

3. The meadow persists as a mantle covering basalt
lava flows 24 million years old! The shallow wet soils
inhibit colonizing trees, but favor low-growing
meadow plants.

4. Horse Rock Ridge is perhaps named for a basalt dike
near the upper part of the reserve. From some
views, it may resemble a horse or horses to some.

5. Upon entering the
meadow after a
short climb from the
parking area, this
was the first plant to
catch our attention.
Fields of shooting
star, Dodecatheon
hendersonii,
blanketed moist
areas of the reserve.

6. Nearby, a less common
early spring plant,
Frittilaria lanceolata,
was visible, protected
under shrubs along the
trail.

7. Poor soils foster delightful diminutive forms of
usually larger plants. Pink-flowered and tiny rosy
plectritis, Plectritis congesta, and blue-flowered, but
also tiny blue-eyed Mary, Collinsia sp.

8. Other common
wildflowers were small
patches of bright
yellow-flowered
Lomatium utriculatum
and drifts of Oregon
fawn lily, Erythronium
oreganum.

9. Erigeroncompositus
The striking cut-leaf daisy often appeared near the
edges of basalt ledges.

10. “Weeping” basalt
ledges provide habitat
for water-loving plants.
Yellow monkeyflower,
Mimulus guttatus,
grows profusely in
these areas.

11. Pretty meadow plants from the
darker side. . .
Top : Death camas,
Zigadenus venenosus
(now Toxicoscordion
venenosum), whose
bulbs have been
mistaken for the edible
camas bulb. Bottom:
Annual and parasitic
naked broomrape,
Orobanche uniflora,
which surfaces to flower
and producer seeds.

12. Forest edges hold
other interests. Here a
manzanita,
Arctostaphylos
columbiana, borders
the forest with die-
back in unfavorable
years. Douglas fir,
Pseudotsuga menziesii,
produces cones, and a
wild strawberry,
probably Fragaria
virginiana, flowers
profusely.

13. The entire area offers outstanding views of the
surrounding mountains. This photograph shows the
view looking toward the central Cascade Mountains
to the East. Horse ridge rock is in the foreground.

14. Although clear cuts for timber are common in the
area, the meadow itself, nearly 83 acres, has been
preserved and buffered with the help of local timber
companies. Weyerhaeuser has granted an easement
and surrounding old growth forest to help preserve a
portion of this exceptional area.

15. On our way out of the
reserve, we came
across a rare sight in
the forest. It was the
first time I had seen
the white-flowered
form of this forest
beauty, the fairy
slipper orchid, Calypso
bulbosa.

16. For more information . . .
• http://www.portlandhikersfieldguide
.org/wiki/Horse_Rock_Ridge This
website provides basic information
and directions to the trailhead.
• http://www.npsoregon.org/kalmiops
is/kalmiopsis11/horserockridge.pdf
An article in Kalmiopsis magazine
about this outstanding area.
Includes a species list.
• http://www.fs.fed.us/pnw/pubs/gtr5
71.pdf Pictured at right, this
publication by the Bureau of Land
Management explains more about
the area and provides a species list.

17. Thank you for watching!
• Copyright©, Linda R.
McMahan, Oregon
State University
Extension Service
• This presentation can
be used freely for
educational purposes
• For other uses, please
contact the author at
viomusica@gmail.com
A native Saxifrage, perhaps Saxifraga
occidentalis.