The Pleasant Valley Tulip: A Sensitive Plant Species
by Mike Foster
|
For much of the past four months a great deal of energy and planning has been directed toward the Cleveland Fire Area. An environmental impact statement is being prepared in order to determine how to determine how the forest lands affected by the catastrophic wildfire should be managed to assist in the recovery of the fire-scarred lands. One of the many considerations the Cleveland Fire Recovery Team has to take into account is how to best manage the sensitive plant species that are present in the fire area. Two species were directly affected by the fire. One of these species, Pleasant Valley tulip, will be discussed in a two part article beginning with this issue of the Interpreter.
In order to understand how wildfires affect plants like the Pleasant Valley tulip, it is helpful to know a little about the biology of the plant and the habitats that provide a home for the species. The Pleasant Valley tulip is not a true tulip, but like tulips, it is a member of the Lily family. The scientific name for Pleasant Valley Tulip is Calochortus clavatus var. avius. Calochortus means "beautiful grass" in Greek, the name in obvious reference to the plants's beautiful tulip-like flowers and grass-like leaves.
Calochortus is a moderately large genus, with some 37 species found in California and at least 10 species found on the Eldorado National Forest. The Pleasant Valley tulip is unique among these 10 species because it is only found within the boundaries of the national forest and nowhere else in the world! Of the nine sensitive plant species found on the Forest, the Pleasant Valley tulip is the tallest, has the largest flowers, and is by far the most glamorous.
A non-woody perennial herb, Pleasant Valley tulip reproduces by seed and little bulb-like structures called "bulbils". These bulbils are formed at the base of the lowermost, nearly subterranean leaves and provide a vegetative means of reproduction. Sexual reproduction occurs when pollen is transferred from a flower's anther to a stigma. The pollen is believed to be transferred by flower beetles, with pollen from one flower being transferred to either a stigma of the same flower, or a stigma on another flower of the same or different plant. Pollination occurs during mid-summer, and seeds are dispersed from late summer to late autumn. Wind is apparently the chief means of seed dispersal.
After the seeds germinate in winter, young plants will produce single, grass like leaves that are long, v-shaped, and mostly prostrate. In a given year, about 85 percent of the plants comprising a population produce nothing more that this single, inconspicuous leaf. This single leaf is evident from March or April through May or June before it dries and withers away, the plant surviving the summer/fall drought as a dormant bulb.
The age at which these plants produce flowers is not known. Based on observations of other members of the genus Calochortus, it is thought that Pleasant Valley tulip does not produce flowers until its fourth or fifth year. The flowering stems are erect, can reach hip height, and can bear from 1 to 6 gorgeous flowers that defy ready description (see the accompanying drawing, or visit the Cleveland Fire Area for a glimpse of the plant).
Habitat for Pleasant Valley tulip is provided by open stands of mixed conifer forest, scrubby areas on lava caps, and mixed oak/manzanita/pine communities. The most common denominator amongst occurrences of Pleasant Valley tulip is the presence of rocky, cobbey soils and evidence of fire. Most of the locations where this plant is found are between 3,000 and 5, 000 feet elevation on south-facing slopes. A preference for rocky sites has been explained by two separate and untested hypotheses. Some speculate that Pleasant Valley tulip is restricted to rocky sites in order to "prevent" foraging gophers from munching on its relatively delectable bulb. Others wonder if the plant is not capable of competing with the other plant species found on deeper, more fertile soils and is thus less restricted to harsher, less productive sites.
In the next issue, I will relate the above discussions on Pleasant Valley tulip to the Cleveland Fire Area and show how botanists use their knowledge of plants to help design recovery projects to benefit sensitive plant species. The key points to remember from this article are: 1) in any given year, most of the plants that constitute an occurrence are difficult to find due to the lack of distinctive vegetative features; 2) Pleasant Valley tulip possesses a bulb that is usually 3 to 4 inches below the soil surface, nested away under rocks and cobbles; 3) most locations where this plant is found show evidence of recent and repeated low intensity fires; and 4) Pleasant Valley tulip is frequently found in areas that have infertile, rocky soils not suited to intensive timber management.
Continue to Part 3 >
Back to the Top
Back to Main Natural History Page
|
|
