Vernal Pool with Downingia

Vernal Pool with Downingia

Vernal Pools occur where there is moderate to large sized “natural” depression with no outlet. The depression has to be large enough to capture enough rainfall to fill the pond to some depth. The water collects in the lowest point in the depression. There also must be an impervious layer under the pond that prevents the water from seeping deep into the soil. This impervious layer is usually a layer of calcium carbonate that forms where water seeping downward due to gravity is balanced by pull upward caused by evaporation. True vernal pools are a desert or semi-desert phenomenon. I suspect it goes without saying that not all temporary pools are vernal pools. For example, in San Simeon State Park there are extensive interlocking shallow pools surrounding small hillocks that are filled up by winter rains and are gone by summer. These are formed by animals that dig out the depressions and pile up the excavated dirt to form the mounds. This allows the animals a drier den during the rainy season. Back East, where it rains or snows most of the year, you will find temporary ponds that will last from many months. These are colonized by ordinary species more or less identical to those that inhabit the forest around them. Vernal pools will only last anywhere from a few days to a few weeks depending on their size and the amount of rainfall.

For the second Obispoensis of this year, we are doing a repeat of a drawing Bonnie did for the banquet cover back in 1993. We’re repeating this particular drawing because of the drought and in the hope that it will serve as sign that we really, really need rain! It was originally done in honor of Dr. Wayne Ferren’s (then Curator of the Herbarium at U.C. Santa Barbara) program entitled “Creation and Restoration of Vernal Pools at Del Sur Reserve near Isla Vista, California.” The vernal pool in Bonnie’s drawing is one that occurs off the road to leading to Cerro Noroeste from California State Highway 166. It is on a shelf in the otherwise steep slopes of that mountain’s foothills. This particular pool is a favorite stop for CNPS-SLO, especially when there has been enough rainfall to fill it.

It is when the vernal pool lasts for weeks that they become particularly interesting. For plants, vernal pools are a particular challenge. The first plants to appear are those that can stand total emersion in the water. These are aquatic plants that usually live totally submerged in the water. Because the water is going to last for a very short time, these aquatic plants must have an accelerated life cycle to get from germination to fruiting. As the pool begins to dry up, plants that can tolerate saturated soils begin to germinate in a ring just inside and upslope from the water’s edge. Again these plants have a difficult environment. They begin life with too much water and end up high and dry as the pool constricts away from them. The end result of this process is a series of bands produced by various species that get their start under different soil water conditions. This banding is easily visible in Bonnie’s drawing. One genus that is particularly typical of vernal pools Downingia. It is they that form a spectacular bluish band around the pool. Bonnie included a drawing of the flower of the common Downingia species found in this particular pond. It is Downingia cuspidata.

Bonnie’s drawing was taken from a photograph, lost many years ago, that was taken on a chapter field trip to Mount Able and Mt. Pinos. Although the person shown in the drawing is drawn much too small to be recognized, notes from the time indicate that it is Sybil McLeod who served CNPS-SLO chapter in many different ways. Yes, she was also the wife of Dr. Malcolm McLeod who was a past CNPS-SLO President, Historian, and for many years the Rare Plant Committee Chairman. To be a committee chair in this chapter usually means you do all the committee’s work.

by Dirk Walters, illustrations by Bonnie Walters | Dirk and Bonnie Walters are long-time CNPS-SLO members, contributors, and board/committee participants. In addition to his work at Cal Poly, Dirk is the current CNPS-SLO Historian.
Coreopsis Hill

Coreopsis Hill

 

Sunday, March 23, 2019, 8:45 am

Coreopsis Hill (in the Guadalupe-Nipomo Dunes) 

This hike is sponsored by the San Luis Obispo Chapter of CNPS, the US Fish and Wildlife Service, and The Dunes Center, and will be led by Jenny Langford, Lauren Brown, Dirk Walters, and other local botanists and volunteers.

The hike will begin at 9:00 AM (please plan to arrive between 8:45 and 9:00), leaving from the south end of Beigle Road at the USFWS access road (fenced road). It will be a casual walk through the dunes to the top of Coreopsis Hill. This is a moderate hike, about 3 hours round-trip. Dress in layers, bring water and snacks, and have your “Dune Mother’s Wildflower Guide” by Dr. Malcolm McLeod for the trip. Long pants and closed shoes are recommended as the habitat is coastal dune scrub and there is the possibility of poison oak and ticks in the natural dune areas (we will watch for and point these out so they can be
avoided). For more information call Lauren Brown at 805-460-6329 or 805-570-7993. Heavy rain cancels this trip (light rain, bring appropriate clothing).

NOTE: Pets, smoking, or alcohol are not allowed on the refuge, including the parking area, or other properties accessed during the hike (i.e., State Parks and private property). Pets may not be left in cars in the parking areas.

Directions from the north:  Take Hwy 101 south from San Luis Obispo. Turn right (west) at the new Willow Road off ramp (Exit 180). Proceed west on Willow Road for about 4.3 miles, to Highway 1. Turn left (south) on Highway 1 and proceed for 2.7 miles, to Oso Flaco Lake Road. Turn right (west) on Oso Flaco Lake Road. Proceed west on Oso Flaco Lake Road for 2.5 miles to Beigle Road. Look for a 6’ tall wire mesh fence and steel gate.

Directions from the south: Take 101 north to Santa Maria and take the Main Street exit toward the town of Guadalupe. Turn right onto
Highway 1 and head north to Oso Flaco Lake Road (about 3 miles north of Guadalupe), turn left onto Oso Flaco Lake Road and
proceed 2.5 miles to Beigle Road (on left).

Parking: We will have people posted at the entrance of the USFWS fenced road to direct parking. The gate will be open around 8:30. Please do not park on Oso Flaco Lake Road near the gate as there is not much room and it could be hazardous. There should be plenty of room to park along the USFWS access road. The Oso Flaco Lake State Park lot is another ¾ miles west of Beigle Road, if you need to use a restroom before the hike (there are none along the hike route). Note: Pets, smoking or tobacco products, or alcohol are not allowed on the Refuge, including the parking area, or other properties accessed during the hike (i.e., State Parks and Private Property). Pets may not be left in cars in the parking areas.

 Monardella undulata ssp. crispaAdditional Information: The Guadalupe-Nipomo  Dunes Coastal Area contains the largest, relatively undisturbed coastal dune tract in California and was designated a National Natural Landmark in 1974. Five major plant communities are represented including pioneer/foredunes; coastal dune scrub; riparian woodland; coastal dune freshwater marshes, ponds, and swales; and active interior dunes. The flora includes many endemic plant species and the dunes habitats support numerous rare, threatened and endangered plants and animals.

Oenothera deltoides

Oenothera deltoides

Desert Evening Primrose (Oenothera deltoides)

Desert evening primrose (Oenothera deltoides) is in full bloom at Shell Creek as I write this. So it
seemed appropriate to resurrect a drawing Bonnie drew back in 1981. It is one of her earlier drawings since it shows a lot of shading. The flowers are white and the plant starts out as a small mound and then spreads-out across the surface of the ground. It can reach several feet across. Fruits are produced along the full length of the branches. However, if you go to Shell Creek in summer and fall you will probably find little trace of it. This is
because as the branches dry out, they turn upward forming what resembles a largish bird cage. Lastly, the dried plant breaks off and joins the other tumble weeds bouncing around and distributing its seeds.

The species has several common names, including birdcage evening primrose, bird cage plant, basket evening primrose, lion in a cage, and devil’s lantern, or as I’ve been simply calling it, desert evening primrose. As my preferred name implies, it’s found in the deserts, from eastern Washington through California, Nevada, Arizona
and into northern Mexico. The common names that refer to “cages” are references to its bird-cage shape the dried plant takes just before it tumbles away.

According to The Jepson Manual, it has five recognized subspecies. This would be expected by a plant occupying such a large range with so many variations in habitat. It prefers well drained soils so it is very common on desert sand dunes thus another common name is dune evening primrose. In our area it is found in the valleys of the interior Coast Ranges, especially in sandy or well drained soils. The area around Shell
Creek is the most northwestern extent of its range of which I’m aware. At Shell Creek it’s most numerous in the sandy alluvial fan east of Shell Creek.

Some of the people on the Malcolm G. McLeod Annual Shell Creek Field Trip might have noticed quite a few of the flowers were fading, desert evening primrose flowers open in the evening and close up in the morning. That is, their large, fragrant, white flowers are open mostly at night when it’s dark.  The white flowers would make them visible in the twilight and darkness. The flowers are very odoriferous at least in the evening. The large, white, night-blooming, odoriferous traits indicate that the species is pollinated by moths, probably hawk moths.

Before 1969, the genus, Oenothera, was huge and included species given the common names evening primrose for the night blooming ones and sun cups for the day flowering ones. Sun cups and evening primroses share, with other members of its family, Onagraceae, four separate petals. In fact, the flowers of the Onagraceae, have a number of distinctive set of characteristics which makes them easy to recognize. They produce flowers that possess four sepals, four petals, eight stamens, attached to the top of a generally thin, often long tube constructed from the bases of the sepals, petals and stamens (hypanthium). The hypanthium arises from the top of the usually four-parted ovary. This means the ovary is said to be inferior or below all the flower parts. This can be summarized asformulaCA4 is short for calyx which is the collective term for the 4 sepals; CO4 stand for the corolla, the collective term for the 4 petals. A8 is the abbreviation for androecium, which translates as the “male things” which are the 8 stamens). G4 stands for gynoecium (female thing) which represents the four-parted ovary, style and/or stigma. The circled four indicates that the 4 subunits (carpels) that make up the gynoecium are fused into a single pistil (visual unit of the gynoecium within a flower). The most conspicuous character that separated plants with the common names, sun cups and evening primroses, is the stigma. A look at Bonnie’s drawing will show it to have four hair-like stigma branches. Only true evening primroses (Oenothera) have this trait. The rest of the old, un-split genus Oenothera display a single wide hemispherical cap. At first, all these species were put into the single genus, Camissonia. Unfortunately this is no longer the case as the knob-stigma species are now scattered into several genera with differences of opinion as to how many. One last point, these are EVENING primroses not primroses. I bring this up because a number of web sites left off the evening in the name evening primroses when giving their lists of common names. I know that common names are not regulated, but to call them simply, primroses, I find totally confusing. True primroses are in the totally unrelated family, Primulaceae. The Primulaceae have flower parts in 5’s. That is, they have 5 sepals, 5 fused petals and 5 stamens placed in front of the petal lobes. The ovary is superior and has only a single cavity, not 4, inside. A common weedy member of the Primulaceae is scarlet pimpernel which is a weed in almost all of our gardens. At least it is in those of us who are not great gardeners.

by Dirk Walters, illustrations by Bonnie Walters | Dirk and Bonnie Walters are long-time CNPS-SLO members, contributors, and board/committee participants. In addition to his work at Cal Poly, Dirk is the current CNPS-SLO Historian.

 

 

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About CNPS & CNPS-SLO ContactJoin The mission of the California Native Plant Society is to increase understanding and appreciation of California’s native plants and to conserve them and their natural habitats through education, science, advocacy,...