Plant Species of the Borrego Desert: 2008-2009 Blooms

Table of Contents

Rainfall This Season

Annual Germination, Growth and Blooms
     General Requirements for Annual Germination
     Summary of Annual Germination, Growth and Blooms in 2008-2009

     Detailed Germination, Growth and Bloom Reports From Each Hike

How Long Will An Annual Bloom Last
     General Factors
     Predictions for This Year

Species in Bloom On Each Trip
     Number of Species and Plants in Bloom On Each Trip
     List of Species in Bloom On Each Trip

Links to Other Webpages on Anza-Borrego Desert State Park Blooms


The Borrego Desert is the northern part of Anza-Borrego Desert State Park below an elevation of 3000 feet, named for the Borrego Valley and the town of Borrego Springs (map and expanded definition).

This page gives some information about the early progress of the 2008-2009 bloom, concentrating on the annuals that are responsible for the widespread showy blooms that appear in some years on the desert floor. The date of the last update to this page is given at the bottom of this page.

In addition to specific information about current conditions, this page also gives some general information on what is needed to germinate those annuals, and what is needed to sustain the annual bloom.

The information here is by no means a definitive list to what is blooming in the Borrego Desert; it only records the species I've seen in bloom on my hikes that occur roughly every fourth day. Because the locations change, the numbers of species in bloom, and the number of plants in bloom, cannot usually be directly compared from trip to trip. However, the information here will give the reader an idea of what the bloom is doing in the Borrego Desert, especially for whether a widespread annual bloom is shaping up or not.

Note that there is often quite a difference in the annual bloom between the moister canyons west of Borrego Springs and the drier areas around the Badlands. Similarly, even within those canyons on the west, there can be large differences between the north-facing and south-facing slopes, and between canyons with permanent water, like Borrego Palm Canyon, and drier canyons. In the drier areas to the east, there can be large differences between the edges of washes and the middle of washes, and between shady canyons and open areas.

The locations for each hike are in the report on annual germination below; more information is given in Botanical Trail Reports in Chronological Order, which usually includes more information about the bloom on each trip.

I will probably only record the detailed information given in this page as long as the number of species in bloom is relatively few. Once many species are in bloom, it would be too much work to record them all. But at that point, most readers will no longer care how well the bloom is progressing, since there will be lots of bloom.

Rainfall This Season

Rainfall is the most important determinant of blooms. Rainfall is usually highest on the mountain slopes, especially on the west edge of the Borrego Desert, and falls off dramatically with lower elevation to the east. I've also given the rainfall from my house in Fallbrook, on the coastal side at 680 feet elevation, to show the large difference in rainfall between the wet side of the mountains and the dry side.

The following table gives the storm totals, in inches, as of the last day of each storm. The storm totals were taken from the Weather Service Rainfall Storm Summary, except for Fallbrook and the Borrego Badlands. There is no weather station in the Borrego Badlands; the rainfall estimates are just guesses made from how wet the area appears on trips there. If a station didn't appear in the summary, I assumed the rainfall total was zero. Although this assumption is probably usually correct, it is not necessarily always valid since missing data plague all rain reports.

DateFallbrookSan FelipeAgua CalienteBorrego Palm CanyonBorrego SpringsBorrego Badlands
8 August 20080.00?????
4 November 20080.
27 November 20081.810.510.520.310.35~0.30
15 December 20082.400.980.150.750.47~0.4?
17 December 20081.610.872.131.141.54~1.5?
22 December 20080.510.
25 December 20080.510.
3 January 20090.
23 January 20090.
26 January 20090.
Total Since 1 October7.402.482.802.202.38~2.2?

Annual Germination, Growth and Blooms

General Requirements for Annual Germination

The timing of rainfall is extremely important for the annual bloom. Rainfall received in the summer and early fall will not germinate the annuals that bloom in February and March. Rainfall received after January will either not germinate those annuals, or will germinate them too late for them to produce a robust bloom in most years. Thus rain must fall in October, November, and/or December in order to germinate the annuals that produce the showy mass displays.

The amount in a single storm is also important. Native annuals require about an inch of rainfall, received over no longer than a period of something like several days, in order to germinate. Our native annuals have learned the hard way that any less rainfall doesn't guarantee enough moisture in the soil for them to produce seeds.

Unfortunately, non-native annuals can germinate on less rainfall, and can sometimes get a head start over our native annuals if we get a first rainfall much less than an inch.

See Predicting Desert Wildflower Blooms - The science behind the spectacle from the Arizona-Sonora Desert Museum for information relating to Arizona desert blooms.

Summary of Annual Germination, Growth and Blooms in 2008-2009

In 2008-2009, we received rain just in the nick of time for a fairly widespread germination of most of the annual species in many places. Unfortunately, we have gotten no further rain. As of 31 January 2009, we have gone 45 days without rain.

The first annuals have begun to bloom, and many annual species are sending up their bloom stalks with buds. Many annuals will have begun blooming by mid-February. The time of their peak bloom cannot be predicted now.

The first annuals were observed in bloom on 19 January 2009, of the non-native Asian mustard, Brassica tournefortii, and it was not an encouraging sight. They were only a few inches high, and will produce only a few flowers per plant. They were next to dead plants from last year that produced hundreds of flowers per plant. If we do not get more rain soon, many of the other annuals will bloom similarly pathetically.

Michael Charters shows some of the first annual blooms in Butler Canyon from 24 January 2009, which also came from small plants with only a few blooms per plant. The annual species in bloom there were common phacelia, Phacelia distans; small-flowered poppy, Eschscholzia minutiflora; and curvenut combseed, Pectocarya recurvata.

A few shrub species are already in peak bloom in some areas. Bladderpod, Isomeris arborea, was in peak bloom in Rockhouse Canyon below Hidden Spring on 15 and 28 January 2009. Desert-lavender, Hyptis emoryi, was in peak bloom there on 28 January 2009.

Additional perennial and shrub plant species are coming into bloom regularly. For example, the first desert apricot, Prunus fremontii, bloom appeared in Henderson Canyon on 7 January. The first Borrego milk-vetch, Astragalus lentiginosus var. borreganus was observed in bloom on 19 January in Palm Wash.

Rock crossosoma, Crossosoma bigelovii; and wishbone plant, Mirabilis bigelovii, had buds in Henderson Canyon on 12 January there and will begin blooming by roughly 1 February. One plant of desert lily, Hesperocallis undulata, had tiny buds on 19 January 2009 in Palm Wash, and may begin blooming in early February.

Detailed Germination, Growth and Bloom Reports From Each Hike

11/28/08: Santa Rosa Mountains, Coachwhip Canyon. No annuals observed, but it was only a day or two after the rain, too early to expect any annuals to have germinated.

12/4/08: Borrego Badlands, Ella Wash / Vista del Malpais Wash / Smoke Tree Wash. No seedlings observed along the 8 miles surveyed except in a single location in Smoke Tree Wash somewhat south of S22. There were two circular small patches of the invasive non-native Asian mustard, Brassica tournefortii, which I pulled out, and one small patch of Cryptantha seedlings.

12/9/08: Clark Valley. Germination is sparse, with only the invasive non-native Asian mustard, Brassica tournefortii, germinating here and there on the Valley floor. In the base of a channel on the alluvial slope of the Santa Rosa Mountains, there were a handful of baby annuals of phacelia and Cryptantha.

12/12/08: Clark Valley. Germination is still sparse, with mostly only the invasive non-native Asian mustard, Brassica tournefortii, germinating here and there on the Valley floor. There were a small number of native annuals such as lupine and possibly Schott's calico, Loeseliastrum schottii, that had germinated in a sandy area west of Clark Lake.

12/19/08: S22; Arroyo Salado, 17 Palms, Una Palma, Five Palms. The S22 roadsides near Borrego Springs have turned green from the mostly non-native annuals that had sprouted there. On our hike, most areas still had no annual germination, but it was too early to expect much so soon after the rain. This area has very few Brassica tournefortii so far, but we found and eliminated ~20 patches of seedlings up, most of which had germinated from the November rain. Several areas that had wet mud at the surface had considerable germination of native annuals.

12/23/08: S22; Borrego Sink, Spring. There is now widespread dense sickening-to-see germination of the non-native Schismus barbatus and Brassica tournefortii in these areas of dense Brassica tournefortii infestation: along S22 east of Borrego Springs to Palm Canyon Road east, Palm Canyon Road east down to the Borrego Dump, and along the wash from the Badlands that is east of the north-south section of S22. Some native annuals are up in that area, such as dune primrose, Oenothera deltoides, but they are outnumbered by a factor of 100 to 1,000.

In the very alkaline area of the Borrego Sink and Spring, the non-native infestation is still low, but the Brassica and Schismus still outnumbered native annuals by the same factor. We only saw a small number of Cryptantha seedlings, and a single seedling of bottlebrush, Camissonia boothii.

12/29/08: Henderson Canyon. I expected there to be widespread annual germination in this desert-edge environment compared to the open-desert alkaline environments of my previous trips this year, and there was. However, the patterns in the germination were unexpected.

In the parking area at the middle of the farthest point of the mouth of Henderson Canyon, the germination was not widespread. It was mostly confined to areas such as the base of rocks, underneath shrubs, and on north-facing shady walls of washes and the nearby wash areas.

Interestingly, there were two age classes of annuals, some that had germinated from the 27 November rain, and others than had germinated from the 15-17 December rain. For example, seedlings of common phacelia, Phacelia distans, had only their cotyledons in areas receiving only direct rainfall, but had an additional four quite large true leaves in areas at the base of boulders that received runoff from those boulders. See these examples.

The bigger phacelias are about equivalent to the ones observed last year at day 38 after its first germinating rainfall (it was day 32 after the 27 November rain on 12/29/08).

The floor of the wash had little germination, despite the presence of many dead remnants of annuals from previous years. For example, we saw numerous patches of dead remnant California suncup, Camissonia californica, plants that had at most a very few baby annuals. However, the few seedlings of this species were much smaller than those of other species that had germinated in nearby areas. So it is possible this species just takes longer to germinate, and a robust germination may still take place.

Seedlings of brown-eyed primrose, Camissonia claviformis, and pale sun-cup, C. pallida, were totally absent everywhere. There were dense carpets of dead C. claviformis from last spring with not a single seedling anywhere on our survey.

As we approached the north-facing slopes of Henderson Canyon, the germination increased, echoing the pattern of germination on the north-facing banks in the low-relief east-west washes. The flats out in the open began to have a good cover of annuals. When we got to the slopes themselves, annual germination was widespread, with the perennials making an appearance as well.

1/2/09: Henderson Canyon. Conditions similar to 12/29/08, with the baby annuals just a bit bigger. No new species were noted as germinating. Buds of desert apricot, Prunus fremontii, are showing color.

1/7/09: Henderson Canyon. Conditions similar to 1/2/09, with the baby annuals just a bit bigger. Three new species were noted as germinating, California suncup, Camissonia californica; brown-eyed primrose, C. claviformis ssp. peirsonii; and curvenut combseed, Pectocarya recurvata, which has turned some north-facing hillsides green. In contrast to the combseed, the number of Camissonia seedlings seen so far is very sparse, some 100 to 1,000 times fewer than last year.

The first flowers of desert apricot, Prunus fremontii, have opened.

Some patches of south-facing hillsides have now turned green from new growth on brittlebush, Encelia farinosa.

1/12/09: Henderson Canyon. Conditions similar to 1/7/09, with the annuals still growing. Some Phacelia distans plants are getting quite large. Newly-germinated annuals, mostly Phacelia distans and Pholistoma membranaceum, are still appearing in a few moist shady spots! Rock crossosoma, Crossosoma bigelovii; and wishbone plant, Mirabilis bigelovii, now have buds.

1/12/09: Rockhouse Canyon. The portion of the canyon below Hidden Spring has hundreds of plants total of four species in bloom: bladderpod, Isomeris arborea; punctate rabbitbrush, Chrysothamnus paniculatus; sweetbush, Bebbia juncea; and desert-lavender, Hyptis emoryi. Bladderpod is in full bloom; desert lavender is beginning its bloom, and the other two species are ending their bloom. It won't be long before wishbone plant, Mirabilis bigelovii, joins them in bloom.

There is decent annual germination here, although some of the annuals looked like they could use some rain.

1/19/09: Palm Wash. Many annuals and perennials are present along S22 near the entrance to Palm Wash, which is very encouraging. None are showing buds yet.

The first annuals were observed in bloom today at one spot in Palm Wash, pathetically-small specimens of the non-native Asian mustard, Brassica tournefortii. It was not an encouraging sight. They were only a few inches high, and will produce only a few flowers per plant. They were next to dead plants from last year that produced hundreds of flowers per plant. If we do not get more rain soon, many of the other annuals will bloom similarly pathetically.

Many plants of desert holly, Atriplex hymenelytra, were in full bloom. Desert tobacco, Nicotiana obtusifolia, was just beginning to bloom. One beautiful specimen of Borrego milk-vetch, Astragalus lentiginosus var. borreganus, was beginning its bloom.

1/24/09: Butler Canyon. The annuals are popping! We came across the first blooms of common phacelia, Phacelia distans; small-flowered poppy, Eschscholzia minutiflora; and even the first FRUIT of curvenut combseed, Pectocarya recurvata.

There were buds and/or the beginning flower stalks on a number of annual species, as well as buds on perennials and shrubs like cheesebush, Hymenoclea salsola; and rambling milkweed, Sarcostemma hirtellum. Many annual species will have their first blooms within weeks.

Not coincidentally, insects were out as well. Butterflies were mobbing a desert-thorn, Lycium brevipes, in bloom at Clark Lake.

Michael Charters shows some of the annual bloom, which came from small plants with only a few blooms per plant.

1/28/09: Rockhouse Canyon. Bladderpod, Isomeris arborea continues to be in full bloom, now joined by desert-lavender, Hyptis emoryi. The bloom of punctate rabbitbrush, Chrysothamnus paniculatus is ending. Buds of wishbone plant, Mirabilis bigelovii, look like they will pop in a week or two.

Although the first bloom of redstem filaree, Erodium cicutarium, was observed, none of the other annuals are as advanced as those in Butler Canyon four days ago.

How Long Will An Annual Bloom Last

General Factors

Past Rainfall, Future Rainfall, and Heat are the main factors determining how long an annual bloom will last on the desert floor at about 1000 feet elevation:

Predictions for This Year

The annual bloom has only barely begun, with just four species in bloom so far, so no predictions can be made.

Species in Bloom On Each Trip

Number of Species and Plants in Bloom On Each Trip

Four plots are given below. The first two plots show what was observed on each trip, the total number of species in bloom and the total number of plants in bloom. The total number of plants in bloom for each individual species is capped at a maximum of 99 plants. The next two plots give the cumulative total numbers from all trips so far this season, of all species seen in bloom and of all annual species that germinated this year and have begun blooming. Thus this does not count any annual species that survived from last year and is now blooming. These cumulative total numbers include the number of species on a given trip as well as those from all trips previous to that trip.

The plots and the table here must be interpreted cautiously, since long hikes will find more plants in bloom. For example, the hikes of 12/29, 1/2 and 1/9 were all in Henderson Canyon, but were 4, 7 and 8 miles long, respectively. The increase in the number of plants was due almost entirely to the length covered.

Hikes in the same general area on successive trips are color-coded in the table headers below. If the color changes between columns, it is a tip-off that different environments, and hence plant species, might have been sampled. There is no significance to the color used; only the change in color is significant.

Number of11/2812/412/912/1212/1912/2312/291/21/71/121/151/191/241/28

List of Species in Bloom On Each Trip

The table gives the number of plants observed to be in bloom for each species on each hike, with a maximum value of 99 plants. Because the hike locations vary, some species will not be present on every hike, so the lack of an entry for a given hike says nothing about whether that species is blooming elsewhere.

The Checklist is sorted first by category, with dicots before monocots, and then by family and scientific name. The Family and Scientific Name are from the Jepson Manual. An asterisk before the Common Name indicates a non-native taxon.

See Plant Family Abbreviations to obtain the full family name from the abbreviations used in the table below.

FAMScientific NameCommon Name11/2812/412/912/1212/1912/2312/291/21/71/121/151/191/241/28
ACAJusticia californicachuparosa      505050502 3020
ASCAsclepias albicanswhite-stemmed milkweed    1      2  
ASCAsclepias subulatarush milkweed2         111 
ASTAmbrosia dumosaburroweed 1            
ASTBebbia juncea var. asperasweetbush2051   11  5073020
ASTChrysothamnus paniculatuspunctate rabbitbrush          99  30
ASTEncelia frutescensbutton encelia 1            
ASTEricameria brachylepisboundary goldenbush       121    
ASTGutierrezia sarothraematchweed         1    
ASTIsocoma acradenia var. acradeniaalkali goldenbush 20 5205     1  
ASTLepidospartum squamatumscale-broom          20  2
ASTPalafoxia arida var. aridadesert needle    1        2
ASTPeucephyllum schottiipygmy-cedar           3  
ASTStephanomeria pauciflora var. pauciflorawire-lettuce2020  3232222   
ASTXylorhiza orcuttiiOrcutt's woody-aster    2         
BORPectocarya recurvatacurvenut combseed            1 
BRABrassica tournefortiiAsian mustard           20  
CACMammillaria dioicaCalifornia fish-hook cactus             1
CAPIsomeris arboreabladderpod          99 299
CHEAtriplex hymenelytradesert holly           20  
EUPChamaesyce polycarpasmall-seeded spurge    2 5   5   
EUPDitaxis lanceolatanarrowleaf ditaxis      2  22 32
FABAstragalus lentiginosus var. borreganusBorrego milk-vetch           1  
FABCercidium floridum ssp. floridumblue palo verde 1            
FABLotus rigidusdesert lotus          1  1
FABMarina parryiParry's marina          1   
FABPsorothamnus emoryiEmory's indigo-bush1    5     11 
FOUFouquieria splendens ssp. splendensocotillo2      371010355
GERErodium cicutariumredstem filaree             1
HYDPhacelia distanscommon phacelia            3 
KRAKrameria grayiwhite rhatany 1            
LAMHyptis emoryidesert-lavender 1    1 1230 2099
LAMSalvia eremostachyadesert sage             1
PAPEschscholzia minutiflora ssp. minutiflorasmall-flowered poppy            3 
POLEriogonum deflexum var. deflexumflat-topped buckwheat3             
POLEriogonum inflatumdesert trumpet11  1  111 105 
POLEriogonum wrightii var. nodosumWright's buckwheat      53030302  10
ROSPrunus fremontiidesert apricot        1     
RUTThamnosma montanaturpentine broom          1 12
SOLLycium andersoniiAnderson's desert-thorn            2 
SOLLycium brevipes var. brevipesdesert-thorn    310      10 
SOLNicotiana obtusifoliadesert tobacco           42 
SOLPhysalis crassifoliathick-leaved ground cherry            11
VISPhoradendron californicumdesert mistletoe             1
ZYGLarrea tridentatacreosote bush 11       21 1
POACynodon dactylonBermuda grass             1
POAPennisetum setaceumfountain grass          1  1
POAPleuraphis rigidabig galleta            3 

Links to Other Webpages, etc. on Anza-Borrego Desert State Park Blooms

DesertUSA Anza-Borrego Desert State Park Wildflower Reports For 2009

Anza-Borrego Desert Wildflowers: Where and When to Look from the Anza-Borrego Desert Natural History Association

Anza-Borrego Desert State Park Wildflower Hotline: (760)767-4684. "Information on this recording is updated regularly."

Anza-Borrego Foundation and Institute Wildflowers

Theodore Payne Wildflower Hotline (Reports begin on 6 March 2009)

Carol Leigh's California Wildflower Hotsheet

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Copyright © 2008-2009 by Tom Chester.
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Comments and feedback: Tom Chester
Updated 31 January 2009.