Wild (California, yellow, or grass) violet, pansy or Johnny –jump-up
This botanical illustration was created by Mardi Niles using a Micron 005 #1 Archival Ink pen and Prismacolor Verithin colored pencils on Bristol Regular paper. It will be the first of several beautiful pieces of native plant art by Mardi you will be seeing on our covers into the near future.
Viola pedunculata is widespread throughout the coastal portion of our chapter area. It extends inland as far as there is enough moisture. Dr. Hoover reports that it is apparently absent from the desert portions of our county such as the Carrizo Plains. It is always a visible treat (more…)
Author: WOODY FREY, Professor emeritus, OH Department, CalPoly, San Luis Obispo. This article was first published in Pacific Horticulture and is reprinted here with permission.
Six miles north of San Luis Obispo, California, up a winding road off Highway 101 at an altitude of about 2,500 feet is what the locals call Cuesta Ridge. Here is found a remarkable grove of trees some 700 acres of Cupressus sargentii. The area, which is known as the Sargent Cypress Forest, was first mentioned in the 1900s by a U.S. Geological Survey team. Charles Sprague Sargent included the tree in the description of Cupressus goveniana in his Silva North America (1896). Willis Lynn Jepson named C. sargentii in honor of Sargent, author of the monumental Silva and first director of the Arnold Arboretum. Image: By Eric in SF
Sargent cypress forests form plant communities found only in California on serpentine soil atop fog-shrouded mountains from Zaca Peak in Santa Barbara County to Red Mountain in Mendocino County. The forest on Cuesta Ridge, in the Santa Lucia Mountains of San Luis Obispo County, is the only undeveloped site that can be easily visited. A paved road was built along the ridge and through the forest as part of a firebreak system in the late 1960s. Sargent cypress trees in this area grow close together and forty to fifty feet in height. Their lower branches fall and the trunks become bare with fibrous, rough, dark reddish or grayish brown to almost black bark. Many trees, especially along the road, have had additional branches removed as part of the early firebreak activities. Looking through the forest of older trees and seeing these pole-like trunks one may imagine that they have been conveniently placed to support a thousand hammocks. Sargent cypress forms a fire-dependent closed cone coniferous plant community. The cones, which remain on the trees for many years, need heat to open and to treat the seeds for germination. Since there has not been a significant fire in the area since the late 1930s, there are few seedlings. Sites of many old fires, however, are evident from the even-aged stands of reseeded trees that give the scene an undulating checker board pattern.
(Obispoensis editor’s note… since this article was published, the Highway 41 fire swept unevenly through the forest and hundred of trees sprouted in the ashes).
Many of the trees appearing to be seedlings are in fact stunted due to poor soil and harsh growing conditions on the exposed ridge. Pygmy forests of stunted trees can be seen in some areas. The soil is derived from serpentine rock formed during the Jurassic Age. Exposed to air and moisture it turns reddish from large deposits of waterborne iron. The soil is alkaline, coarse, gravelly, porous, highly mineralized, low in calcium and high in magnesium. Although thirty to fifty inches of rain fall each year, most is quickly lost through the loose soil. Plants in this area probably depend on moisture from fog to survive. The tree line seems to follow the mean fog line, and the forest starts and stops abruptly because of this. There are some unusual plants in the Sargent cypress forest, many of which show forms and shapes adapted to the serpentine soil darker green and thicker leaves, bushier, more compact habit, and brighter flowers. Many of these plants have considerable ornamental potential.
Sketch of Cupressus sargentii by Bonnie Walters
Bulbous plants, found deep in the soil, may last many years. One plant of Chlorogalum pomeridianum var. pomeridianum (soap plant) I have been keeping track of for twenty-five years. Zigadenus fremontii is most common, Friiillaria biflora and F. lanceolata, the chocolate and checkered lilies, are sparse. A special treat in late spring is Calochortus obispoensis, with its hairy, multi-colored petals.
Carex obispoensis covers the damp forest floor in many places, remaining green during the summer from the fog that condenses on overhanging branches and drips to the ground. Sidalcea hickmanii ssp. anomala is a rare spring-blooming herbaceous perennial in the Malvaceae that is endemic in the forest’s northwest edge. (Obispoensis editor’s note… after the Highway 41 fire the Sidalcea became very common for a few years) Chorizanihe breweri, a low and compact herbaceous buckwheat, grows in reddish drifts in open spaces on the rocky soil. A rock fern, Onychium densum (Indian’s dreams or cliff-brake), is common elsewhere, but rare this far south. Unusual strains of Ceanothus cuneatus (buck brush) have flowers of a much brighter blue than those found elsewhere in California. Monardella palmeri, a pennyroyal, is associated with the serpentine soil; on hot days it permeates the air with its pungent minty odor.
A visit to the area is always worthwhile if only to enjoy the outstanding views from the ridge. But spring is perhaps the best time to visit. Everything is fresh and green; most plants are in bloom; and the lichens present a kaleidoscopic display of color and pattern. The chaparral on the outskirts of the forest also is in bloom – Fremontodendron califomicum var. obispoense spills its yellow flowers over the ground; Ceanothus foliosus and
Dendromecon rigida with their blue and yellow flowers stand out against the backdrop of the magnificent Actostaphylos obispoensis, a taller shrub with pink or white flowers.
Although the forest and its surroundings have been touched by mining from the early 1900s to the 1950s and by the firebreak activities of the 1960s, the area has not experienced much development. For this reason, in 1968 the Sargent Cypress Forest and surrounding areas totaling 1,300 acres within the Los Padres National Forest were designated a botanical reserve.
(Obispoensis editor’s note…I thought we have enough about the Carrizo Plain, and as there is a new road into the Cypress grove, it would be a worthwhile excursion for coastal folks. Thanks to Heather and Jim Johnson for finding this great article Older members will recall that our chapter got formed as a result of conservation activism against a giant firebreak that USFS was planning through the heart of the tree grove. Visitors will now see a “doghair forest”, where trees are crowded together, small and in competition with each other for resources. This is typical after wildfire results in simultaneous seed release).
The cover drawing and article for this issue of the OBISPOENSIS was written and drawn by Alice Meyer. She was a very active member (and first Hoover Award Recipient in the 1970 and 80’s. She is the one who named our newsletter, OBISPOENSIS, and served as its editor (and typist) for the many years. She is also responsible for setting up the first successful chapter plant sales as well as recruiting our current Plant Sale Chair. She didn’t restrict herself to CNPS. She was also active in the Morro Bay Audubon to which she submitted a number of articles entitled “MEET A NATIVE PLANT’. Below is one of those articles. It was chosen since milkweeds are so important in the conservation of the Monarch butterfly and is being encouraged as a garden plant. Members of this genus serve as the primary food source for Monarch butterfly larva. While eating the milkweed leaves, the larva incorporate the milkweed toxins into their bodies and its these milkweed toxins that protect the Monarch larva from most predators.
I do need to mention a taxonomic update. In her first paragraph Alice places the milkweeds in the taxonomic family, Asclepiadaceae. This was where it was placed up until the 1990’s. Today the two families of milky sapped species [milkweeds (Asclepias) and dogbanes (Apocynum)] have been combined into the single family, Apocynaceae. Milkweeds are primarily temperate in distribution while the dogbane relatives are primarily tropical. Classical taxonomic work always accepted these two families as very closely related. Modern taxonomic studies (including DNA work) have discover the relationships to be intertwined which required their unification into a single family. A number of these formally separated but closely related families have now been combined.
MEET A NATIVE PLANT Asclepias eriocarpus
Milkweed is a perennial plant of the milkweed family (Asclepidiaceae) family. The species shown is common in the Coast Ranges, Sierra Foothills south to Coastal Southern California from 100 to 2000 ft. The species shown is Asclepias eriocarpa (as-KLEP-i-as aor-ee-CARP-a). Monarch butterflies lay their eggs on this plant. The plants are erect and sturdy from 18-36” tall, with leaves 3-4” long, in whorls of 3 or 4 leaves. These are covered with fine hairs, which make them look and feel like flannel. Stems and leaves contain a milky juice, a form of latex.
The clusters of flowers appear in May at the ends of stems between the leaves. The structure of the flowers is very unusual. The corolla is cut into 5 petals. These are turned down so the hide the calyx. The stamens stalks are joined into a tube and the five ‘hoods’ are attached to the base of the column; this is the ‘crown’ of corona, and in this species the crown is pink or purplish. It is actually the nectary of the flower. The flower and its stem is creamy white. In the center of the flower is a fleshy column or tube formed by the stalks of the stamens, capped by the stigma, hiding the two tubes of styles leading down to the ovaries.
The pollen in each anther-cell is a waxy mass of different anthers and adjacent masses of different anthers are attached to a cleft gland. This resembles tiny saddle-bags, clipped together, and if a bee catches her foot in the cleft she may pull out and fly away with two pollen masses to fertilize another flower. To do this, she must get her foot caught in the cleft of another flower.
The probabilities of a bee catching a foot in the cleft of two different flowers, first to collect the pollen sacs, then to deposit them in another flower is so remote that this is called ‘lottery pollination’. When a flower is pollinated its stem enlarges and the petals fall off. The calyx remains at the base of the downy seed pod which becomes 3 to 4” long and the remains of the hoods hang on to the tip of the pod for time. When the pod is ripe, and dry, it splits lengthwise, revealing neat rows of seeds, each with a parachute of fine hairs attached. As soon as the these hairs are dry, the seeds will fly away on the wind to be dispersed. Flowers that have not been pollinated along with their stems, wither and fall away.
Oaks have been in the news a lot recently. Essentially all of it has been bad from the Oak’s point of view. First, there was the clearing of valley (Quercus lobata) and blue (Q. douglasii) oaks in the Paso Robles area. and then the spread of Sudden Oak Death (SOD) into our county. The notes along with Bonnie’s drawing were the Obispoensis cover back (more…)
The plant discussed in this issue of the Obispoensis is one that I’ve wanted to take on for a long time, but could never bring myself to ask Bonnie to draw. Since we are using photos to illustrate it by, I think it’s time. One look at the leaves will indicate the reason for my reluctance. The leaves, which are up to four inches long and two inches wide, are divided two or three times into hundreds (thousands) of long, thin, needle-like segments which are weakly aromatic.
The species epithet (millefollium) translates into ‘thousand (mill) leaf (follia). The leaves spiral up the stem getting smaller higher up the stem. The flowers are small and clustered in heads which are themselves crowded into flat topped clusters. Most plants in the wild produce whitish flowers but occasionally one finds plants baring yellowish or pinkish tinged flowers. These have been selected for deeper colors for use in the garden.
There are many sites on the web that offer these ‘colored’ varieties for sale. The species is extremely variable which would be expected by its essentially worldwide range. It’s found throughout the Northern Hemisphere and just about everywhere in the Southern Hemisphere where humans have settled. A plant with such a wide a distribution as well as a strong correlation with human habitats would certainly be considered an introduced weed. I knew it in the roadsides and pastures of the Midwest, North East and in various weedy and native habitats here in California.
So, where is it native?
One can find any answer you want to believe on the Web. In fact, if I’d been asked where it was native before researching this article, I’d have said Eurasia. I found at least one web site that would have agreed with me. However, a majority of botanical sites as well as the Jepson Manual give its native range as “the entire Northern Hemisphere! So accepting it as a California native plant, where does it grow in California. Answer, practically everywhere there’s they can get sufficient water. Yarrow is found from sea level to over 10,000 feet in a wide variety of habitats (including weedy ones) throughout that altitudinal range. One of the better local places to find it is in our coastal dunes where it can be found spreading across the base of dune slip faces. As such it is serves as an important dune stabilizer. I should point out it is that because of its extreme variability common yarrow has had many scientific names applied to it, but recent thinking have reduced most of them to varieties.
How did it get its name?
The genus, Achillea, was applied to the plant by the Father of Taxonomic Botany, Linnaeus himself in the 1700’s. He named it in Honor of the Greek hero, Achilles. Why did he name it after a non-botanical war hero who was killed in the Battle of Troy? Again if one should look up this plant on the Web, one would find lots and lots of sites that discuss its medicinal uses, many with warnings they are not guaranteeing its effectiveness. In the 17-hundreds yarrow was considered a panacea or a cure-all. The story goes that Achilles was charmed and no weapon could harm him. He’d the protection via his mother dipping him in the river Styx when he was a baby. The River Styx was the transport medium for souls to get to Hades (the land of the dead). However his mother was afraid he would drown if she let go of him completely; so she held him by his heel which therefore did NOT come in contact with waters granting protection. So at Troy, Achilles was killed by a poison arrow which nicked his unprotected heel.
Why bring up Achilles Heel? According to the story told by my major Professor, no modern Pharmacopeia (an official list of medicinal plants) contains yarrow. I.e. after extensive testing, experts have determined that yarrow has NO medicinal value. That Achilea millefolium has no medicinal value “is in fact yarrow’s Achilles heel”.
SOME REALLY SILLY PAST YARROW USES (Source: Botanical.com)
Put it under your pillow and you will dream a vision of your future spouse
Snort it as snuff
Stick it up your nose to either (a) stop a nose bleed, or (b) to start a nose bleed to let blood out of your head to relieve a headache
Stick it in the other end and it stops your piles from bleeding
Use it as a shampoo and it will prevent baldness
Use it in Devil Worship… it was once called ‘The Devil’s Nettle” and maybe not so silly… it was a salad ingredient in the 17th Century, and was mixed with hops to make a more potent beer in Sweden and parts of Africa. Now your’e talking.
Caliente Mountain is the highest spot in the County, and forms the western side of Carrizo Plain National Monument
The oak on Caliente Mountain. is Tucker’s oak, a scrub oak with blue-green, spiny leaves that stands a little over head height but can reach to 7 meters. Quercus john-tuckeri, as it is properly called, is named after John Tucker (1916-2008), Professor of Plant Science at U.C.Davis who also wrote the oak treatment in the Jepson Manual.
Hoover in his “Vascular Plants of San Luis Obispo County” called the oak Quercus dumosa var. turbinella, and that, at that time, Tucker called the same tree Quercus turbinella sap. californica. Added to the confusion is known hybridization with blue oak, Quercus douglasii. The oak is mixed in with California juniper, Juniperus californica, and a mix of chaparral plants including chamise. This association of oak and juniper ca also be found in the uplands of the Great Basin and Arizona, although the species are different. This is part of the great “P-J”, the pinyon pine- juniper association that is very common in the uplands of the arid west.
The “P” of the “PJ” is rare in the Caliente Range, but much more common on the flanks to Mt. Pinos to the southeast. Both oak and juniper are present at the summit. The balance between them varies from place to place, with the junipers seeming to tolerate slightly drier sites than the oak.
You can visit this interesting plant association by driving up the dirt road toward Selby Campground, and branching to the right just before the campground. The road is drivable in a vehicle with normal clearance, but is narrow in places and has some steep drop-offs. During the droughty spring of 2016 there were still a lot of flowers to be found along the road, including a lot of wind poppies (Stylomecon heterophylla) and yellow sheets of Monolopia.
Oak’s companion on Caliente Mt. is the California juniper, Juniperus californica. It is here seen with its distinctive blue-grey berries. These are not true berries, but cones with merged fleshy scales. Berries are very bitter, and were/are used in the flavoring of gin. Gin’s name is derived from the French and Dutch word for juniper.
You don’t have to go all the way to the top of Caliente Mt., as there are large stands along Highway 58 between Navajo Creek and the Carrizo Plain. Another large stand lies on the north slope of the ridge that borders Highway 58 between La Panza Road and Shell Creek.
The stand near Shell Creek is an excellent example of the control of vegetation by slope aspect, as the south facing slope of the ridge is grass covered and has almost no trees. This can be seen as you drive east on Highway 58 toward La Panza Road.
O.K…. so we’re not Vermont. However we do have some pretty fall color displays. If you like the gold of aspen, you will see the same colors in our closely related cottonwood stands, both trees belonging to the genus Populus. (more…)
October and November are when our Chapter gets serious about growing native plants. We have a November meeting devoted to it as well as our annual plant sale. This got me to remembering some articles written and drawings drawn by Alice G. Meyer that are in the Historians files. The mechanical typewriter written and her hand drawn copies on are on 8½ x 14 paper. I don’t think they were published in our chapter newsletter as I don’t remember us ever using that format. I think Alice may have produced them back in the 1970s or 1980s for the Morro Coast Audubon Society. If so, I hope they will forgive us for reprinting them. They’re too good to lie forgotten in a file somewhere.
Alice, along with her husband, Henry (Bud), were our Chapters first members to be elected Fellows of the State CNPS. Alice was extremely interested in native plant gardening and had a fantastic native plant garden in her Los Osos back yard.
Alice and Bud Meyer: Fellows of CNPS
It was Alice who suggested in the Early 1970’s that our Chapter have a Native Plant Sale! She then went ahead and planned it. The first one was small and contained only plants grown by Chapter members as well as a few plants propagated by Cal Poly Students in a Native Plants Class several years before and that were scheduled to be thrown out. It was quite successful! The Chapter has had a plant sale the first Saturday in November ever since.
Alice ran the sale until 1990 when the current plant Sale Chair, John Nowak, took over. Note, we have had ONLY two plant sale chairs since the early 1970s. This points out one of the strengths in our Chapter. Our member often have a long term commitment to the tasks required for running a CNPS Chapter.
Enough history, let’s let Alice tell us about a fantastic native garden plant in her own words.
Dr. Dirk Walters
PLANT OF THE MONTH
by Alice G. Meyer
The Hearst mountain lilac grows on low hills near the coast, just north and south of Arroyo de la Cruz on the Hearst Ranch. It is not known to grow anywhere else, and, is a rare and endangered plant. It is a spreading prostrate shrub, known botanically as Ceanothus hearstiorum (See-an-OH-thus hearst-ee-OH rum). Horticulturally, it is an ideal ground cover, 4 to 8 inches tall, handsome all year , but especially when it flowers in March and April. The shrub is not widely available, but some growers do propagate it.
Hearst mountain lilac grows best on the coast, in full sun. Inland, it prefers filtered sunlight, and should have some supplemental water during the hot months. Once established, it will survive on the coast with normal rainfall, but will tolerate some summer water. In dry years it needs extra moisture to maintain it best appearance. An observant gardener will note stress and take necessary action. Inland supplemental water during the hot months is a must.
Wherever it is grown, good drainage is important, and there should be no basin around the shrub as water standing around the trunk will cause bacterial problems. When planting, it is better to plant it on a slight mound, so that water runs outward towards the drip line, but the soil should not be piled up around it higher than it was in the container.
The edges of the dark green leaves are curled downward between the veins, making them seem notched and giving the leaves a crinkled appearance.
The deep wedge-wood blue flowers are in tight, upward facing racemes ½ to 1½ inches long.
Each flower is no more than 1/8 inch across.
If you remove one flower and inspect it with a magnifying glass you will find that it has a stem (pedicel) of the same color as the flower, and the five pointed sepals fold inward to the center around the three-parted stigma.
The spaces between the petals are like five rays extending from the center to the edge of the flower.
Near the outer edge of each ‘ray’ a yellow stamen rises, and at the very edge another petal extends outward. This petal is thread-like at the base, and at its outer edge it widens out to a spoon-like shape with a bowl about 1/16 inch long.
Because the flowers are so small, a great many are crowded into each raceme. The groups are beautiful, but close inspection of an individual blossom reveals its complex structure.
Should you grow this shrub, it is advisable not to let too many layers of branches build up on top of the shrub, as it will tend to die out underneath. Keep the shrub very prostrate. Where the plant is native, it is browsed by deer and cattle, and this tendency is thus resolved.
California Goldenrod (Solidago velutina ssp. californica or S. californica)
The photo by Dr. David Chipping that accompanies this note are of the California goldenrod (Solidago velutina ssp. californica or Solidago californica). According to Dr. Hoover in his Vascular Plants of San Luis Obispo County, California goldenrod is found primarily in sandy soils in the western portion of our county.. It prefers open grasslands or edges of wood and shrub lands. It never seems to me to be overly abundant. The currently recognized species (S. velutina) can be found throughout the Western North America from Mexico in to southern Canada. As might be expected of a species with this wide a range, it has been subdivided in a number of sub-specific units. And this is certainly the case. Only two of the subspecies are likely to be encountered in California (S. v. ssp. californica and S. v. ssp. sparsiflora). Subspecies sparsifolia need not concern us here as it is found primarily in Eastern California and
adjacent states. Subspecies californica is found throughout California (except the S.E. Deserts) but is especially common in the California Floristic Province
which includes essentially all of California west of the Cascade, Sierra Nevada, and Peninsular Range axis. In the Morro Bay area I’ve seen it in the grasslands around Shark Inlet.
In Dr. Hoover’s Flora this plant is recognized as S. californica. In the most recent Jepson Manual, S. californica has been reduced to a subspecies of S. velutina. How can this happen? Is it just the whim of the experts? According to the internet, relatively recent numerical taxonomic work on a number of similar, but separately described species of goldenrod indicated that they were more closely related than previously thought. That they were separately described as species should be expected. Until recent advances in communication, taxonomists tended to do plant identification studies primarily on the
plants of their immediate area. They would have had little opportunity to travel and visit reference collections far from home. They would encounter forms of plants that were readily distinguishable from other plants in their area. So why not describe them as a new species. Now, of course, taxonomists have many more tools to help them find characters unknowable to earlier workers. Mass transit and communication help modern taxonomists to know what others have done or are doing. Equally important they have computers to help analyze all this data. So why not expect lots of changes.
In my limited search of the literature and internet, I found three common names. These are velvety goldenrod in Jepson and California goldenrod or 3-nerve goldenrod everywhere else. The name goldenrod I think refers to my observation that most of them produce clusters on unbranched stems (= “rods”) topped with clusters of bright golden flowers (i.e. ‘gold bearing rods’). Most of the plants answering to the California goldenrod subspecies have densely fuzzy or velvet leaves. 3-nerved golden rod refers to the fact that a ‘few’ of the larger plants produce leaves with 3 major veins running from base to tip. I suggest this is not the best common name as it is misleading as only a few of the largest plants produce 3-veined leaves. California goldenrod is the best as this subspecies is essentially restricted to our state.
California goldenrod is highly recommended for the native plant garden. It prefers moist soils but is relatively tolerant of drier soils from sandy to light clay. It’s going to do best in sunny locations. It is attractive to a number of different classes of pollinators so it is great for those who would like to encourage beautiful, beneficial insects to visit their garden. Lastly, one internet site showed pictures of yarn dyed a beautiful yellow color using extracts from California goldenrod..
One last thing about goldenrods in general. Where I grew up, in the Midwest, there were a large number of species of goldenrods and they were exceptionally widespread and numerous. Many species could even be said to be ‘weedy’. Like a lot of members of the sunflower family, they tended to bloom in the late summer into fall. This is also when another member of the sunflower family bloomed-rag weed (Ambrosia trifida among others).
Rag weeds are unusual composites in that they produce tiny, wind pollinated flowers. Rag weeds were nearly as or more common than goldenrods but because of their tiny flowers many didn’t even recognize they were blooming. However they were blooming and they produced exceedingly huge amount of wind-borne pollen. This made rag weed pollen a major component in allergy forecasts. Unfortunately, announcers would say, “the rag weed and goldenrod pollen counts were high”. I had a botany professor who told the class that goldenrod were included in the forecasts only because it was common and
conspicuous. Goldenrods are insect pollinated and therefore would produce little pollen and that wouldn’t have been released into the air. In fact, it would be sticky so it could stick to the pollinator’s bodies.
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 asCA4 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.