Plant Species of the Borrego Desert: 2008-2009 Blooms

Picture of a field of hairy sand verbena, Abronia villosa; and both the white and yellow versions of brown-eyed primrose, Camissonia claviformis ssp. peirsonii; taken in Coachwhip Canyon on 24 February 2009 at dusk; see also larger version.

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
     Pictures 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.

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. This occurs whenever our rainfall is mostly orographic. However, when rainfall is from convection, the deserts can at times get more rainfall than the coast. (See Precipitation types.)

In addition to desert stations, 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. Occasionally other stations are missing in that report; if so, totals are taken from the Rainfall Summary Map.

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.
7 February 20091.650.910.080.240.310.31?
9 February 20090.630.90?0.370.72?
16 February 20090.55??0.240.58?
Total Since 1 October10.23~5.3?3.5?3.053.99~3.0?

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

Peak bloom began on the desert floor below 1000 feet elevation around 24 February 2009. As of then, all the major flower spots in Borrego Springs had acres of flowers. Many of those locations, such as this one in Coachwhip Canyon on 24 February 2009, have their peak number of flowers now. I observed over 2000 plants of 47 species in bloom in a single day's hike there.

A total of 49 annual species have been observed in bloom as of 24 February 2009 (see detailed list); 111 total species have been observed in bloom so far this season. The canyons on the west side of Borrego Springs, and higher elevations, have not yet reached peak bloom.

Some shrub species have been in peak bloom for some time. Chuparosa, Justicia californica, has been in peak bloom since late December 2008. Bladderpod, Isomeris arborea, has been in peak bloom in Rockhouse Canyon below Hidden Spring since 15 January 2009. Desert-lavender, Hyptis emoryi, has been in peak bloom there since 28 January 2009. Desert apricot, Prunus fremontii, was in peak bloom in Culp Valley and Rockhouse Canyon on 1 February 2009. Wishbone plant, Mirabilis bigelovii, began blooming on 11 February 2009, and is now in full bloom.

A small number of annual species are almost totally absent this year. I've seen only three live plants TOTAL of chia, Salvia columbariae, compared to seeing literally thousands of dead plants from previous years. This species just didn't germinate in most areas this year.

Many annuals are smaller than normal due to no rainfall for 52 days after they germinated on 15-17 December 2008. Fortunately, the inch of rain on 7-9 February 2009, and the half inch of rain on 16 February 2009, helped many plants produce more blooms, and it has turned out to be a decent bloom season after all. In fact, the small size of most of the non-native Asian mustard, Brassica tournefortii, plants is allowing the smaller native plants to produce a better show!

Detailed Germination, Growth and Bloom Reports From Each Hike

Detailed reports from the last month are given here; for earlier reports, see Reports from 28 November 2008 to 28 January 2009.

These reports are just summaries of these conditions from each hike. Many of these hikes have much more complete botanical reports online with additional information; see Plant Trail Reports, San Diego County, 2009.

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.

2/1/09: Rockhouse Canyon. The bloom is similar to that on 1/28/09, with the following three additional annuals now in bloom. There is only a single very small plant of everlasting nest-straw, Stylocline gnaphaloides, that germinated here this year, and it is now in bloom. The first plants of many of the following two non-native annuals, Mediterranean schismus, Schismus barbatus; and Asian mustard, Brassica tournefortii, have begun to bloom here.

One plant of Parish's viguiera, Viguiera parishii, is beginning its bloom. Buds of cheesebush, Hymenoclea salsola, are growing larger and may begin blooming in the next week or two. Small buds have appeared on one plant of beavertail cactus, Opuntia basilaris, and on one plant of brittlebush, Encelia farinosa.

Chuparosa, Justicia californica, is in full bloom in Clark Valley along the Rockhouse Canyon Road.

One plant of brittlebush, Encelia farinosa, is in full bloom along S22 near the bottom of the Montezuma grade, but most plants there are not yet showing buds.

2/5/09: Rockhouse Canyon. The annuals have popped into full bloom at several locations along Rockhouse Canyon Road west of Clark Lake! We spent about an hour photographing about ten annual species that had popped into bloom in the last four days. All the usual suspects were there, including spectacle-pod, Dithyrea californica (one even had its first fruit!); narrow-leaved cryptantha, Cryptantha angustifolia; brown-eyed primrose, Camissonia claviformis ssp. peirsonii; Spanish needle, Palafoxia arida; desert dandelion, Malacothrix glabrata, and hairy sand verbena, Abronia villosa. We found some perennial / subshrub plants of California fagonia, Fagonia laevis, in full bloom there as well. Chuparosa, Justicia californica, continues in full bloom along the Road.

On our car stops along Rockhouse Canyon Road, and hike up Rockhouse Canyon to upper Rockhouse Canyon, we saw over 500 individual specimens of 42 species in bloom. In Rockhouse Canyon, Bladderpod, Isomeris arborea; and desert-lavender, Hyptis emoryi; continue to be in full bloom. In the upper canyon, desert apricot, Prunus fremontii, is still in full bloom, but is near its end.

However, the annuals have not yet begun blooming in most locations here.

2/11/09: Coyote Canyon Road, Box Canyon. There are carpets of flowers now along Coyote Canyon Road, most of them from spectacle-pod, Dithyrea californica, which is in full bloom seemingly everywhere along the Road. Some plants have their first beautiful fruit that looks like spectacles. Dune primrose, Oenothera deltoides; hairy sand-verbena, Abronia villosa var. villosa; and brown-eyed primrose, Camissonia claviformis ssp. peirsonii; have all begun blooming in the area at the end of Di Giorgio Road.

Driving along Coyote Canyon Road reveals new species in bloom regularly, including the first blooms of desert dandelion, Malacothrix glabrata, in a number of places. There is no water at First Crossing, so many passenger cars, driven carefully, can make it to Second Crossing. We were pleased to find a nice patch of longbeak streptanthella, Streptanthella longirostris, between First and Second Crossing.

Most annuals in Box Canyon have not yet begun blooming.

On our car stops along Coyote Canyon Road, and hike up Box Canyon, we saw over 1100 individual specimens of 53 species in bloom!

2/17/09: Rockhouse Canyon Road, Henderson Canyon Road, Coyote Canyon Road, Box Canyon. The carpets of flowers along Coyote Canyon Road are even better, with desert dandelion, Malacothrix glabrata; Fremont pincushion, Chaenactis fremontii; and desert chicory, Rafinesquia neomexicana, beginning to join the show.

Hairy sand-verbena, Abronia villosa var. villosa, is now producing its usual carpets of flowers along S22. The first hairy desert-sunflower, Geraea canescens, blooms have appeared along Henderson Canyon Road.

Buds of desert lily, Hesperocallis undulata, will pop in about a week at S22 and Rockhouse Canyon Road.

On our car stops along Henderson Canyon and Coyote Canyon Roads, and hike up Box Canyon, we saw over 1600 individual specimens of 61 species in bloom!

Most annuals in Box Canyon are still the same, and have not yet begun blooming.

2/20/09: S22, Borrego Dunes Area of Borrego Badlands. This area of the Borrego Badlands probably has the most total blooms of anyplace, but unfortunately 99.9% of the blooms are from the non-native Asian mustard, Brassica tournefortii. However, there are 33 native species in bloom here, including the first blooms of the desert lily, Hesperocallis undulata. There are hundreds of plants here total, and we observed about 50 of them showing off their first blooms.

There are large numbers of hairy sand-verbena, Abronia villosa var. villosa; and dune primrose, Oenothera deltoides, in bloom in a number of locations. We found the first blooms of about 20 plants of hairy desert-sunflower, Geraea canescens, ten stunning plants of Borrego milk-vetch, Astragalus lentiginosus var. borreganus; and five plants of gray desert sunflower, Helianthus niveus ssp. canescens.

2/24/09: Coachwhip Canyon. Peak bloom has begun! We found one lovely field of flowers that can't have any more flowers blooming in the future than are blooming right now.

The roadside of S22 is covered with annuals in flower; we found 31 species in bloom within a 100 foot stretch along the road, and another 16 species in bloom along our hike in Coachwhip Canyon, for a total of 47 species in bloom here. We estimated we saw 1786 individual plants in bloom. Since we capped the count for each species at 99 plants, we easily saw over 2000 individual plants in bloom.

Pictures From Each Hike

Most of my pictures were taken for scientific purposes, and not specifically to show anything about the bloom. However, they may be of interest to people showing some aspects of what the bloom was like on a given date. My pictures are not even on standard webpages; I link to a directory and you have to click on the link for each picture to see it. Scientific names are used almost exclusively for the picture names.

The context for most of these pictures is given in the botanical reports from each hike.

In contrast, on those hikes where Michael Charters came along, he documented most of the plants in bloom, and placed them on standard webpages with common and scientific names. I recommend you click on his pages first.

November 28
December 4
December 9
December 12
December 19
December 23
December 29
January 2
January 7
January 12
January 15
January 19
January 24
January 28
February 1
February 5
February 11
February 17
February 20
February 24

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

So far, we have not had any heat that would end the bloom prematurely. But all it takes is a week or two of temperatures in the 80s to end the bloom at elevations below 1000 feet. Last year, heat arrived in mid-March, and quickly ended the bloom, with most annuals almost completely finished blooming by 1 April.

Species in Bloom On Each Trip

Number of Species and Plants in Bloom On Each Trip

Four plots are given below:

The plots and the table here must be interpreted cautiously, for at least two reasons:

I've added two bars in each plot, that represent the time of peak bloom estimated by Park Rangers. Two bars were needed since I wasn't sure of the meaning of the word between in the Park Rangers statement that they anticipate the peak blooming season to hit between the 3rd week of February and the 2nd week of March, depending on the weather. The lower pink bar extends from the beginning of the third week of February (2/15) and the end of the second week of March (3/14). The upper green bar extends from the end of the third week of February (2/22) to the beginning of the second week of March (3/7).

The following table gives the numbers used for the above plots, for the last two months. For earlier numbers, see Numbers from 28 November 2008 to 28 January 2009. The individual observations used to obtain these numbers are in the List of Species in Bloom On Each Trip.

Number of1/21/71/121/151/191/241/282/12/52/112/172/202/24

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 for each species. This maximum value prevents one species from dominating the total plants in bloom, and makes it much easier on me to keep track of the bloom.

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.

This table gives the number of plants in bloom only since 1 January 2009. Some species thus have no number of plants in bloom listed in this table since they were observed in bloom only on trips prior to that date. For those earlier trips, see list of species seen in bloom from 28 November 2008 through 28 January 2009.

#FAMScientific NameCommon Name1/21/71/121/151/191/241/282/12/52/112/172/202/24
1ACAJusticia californicachuparosa5050502 305079809999  
2ASCAsclepias albicanswhite-stemmed milkweed    2        
3ASCAsclepias subulatarush milkweed   111       
4ASCSarcostemma hirtellumrambling milkweed          1 10
5ASTAmbrosia dumosaburroweed             
6ASTBaccharis salicifoliamule fat         2020  
7ASTBebbia juncea var. asperasweetbush1  5073020103053  
8ASTChaenactis fremontiiFremont pincushion         110 5
9ASTChrysothamnus paniculatuspunctate rabbitbrush   99  30101    
10ASTEncelia farinosabrittlebush         230210
11ASTEncelia frutescensbutton encelia           2 
12ASTEricameria brachylepisboundary goldenbush121          
13ASTGeraea canescenshairy desert-sunflower          10205
14ASTGnaphalium luteo-album*common cudweed          5  
15ASTGutierrezia sarothraematchweed  1    1111  
16ASTHelianthus niveus ssp. canescensgray desert sunflower           5 
17ASTHymenoclea salsola var. salsolacheesebush        150501099
18ASTIsocoma acradenia var. acradeniaalkali goldenbush    1        
19ASTLepidospartum squamatumscale-broom   20  21     
20ASTMalacothrix glabratadesert dandelion        12550110
21ASTMonoptilon bellioidesdesert star            10
22ASTPalafoxia arida var. aridadesert needle      22540405099
23ASTPeucephyllum schottiipygmy-cedar    3        
24ASTPleurocoronis plurisetaarrow-leaf         13  
25ASTRafinesquia neomexicanadesert chicory         230120
26ASTStephanomeria pauciflora var. pauciflorawire-lettuce2222         
27ASTStylocline gnaphaloideseverlasting nest-straw       1     
28ASTTrichoptilium incisumyellow-head            10
29ASTTrixis californica var. californicaCalifornia trixis        1    
30ASTViguiera parishiiParish's viguiera       1521  
31ASTXylorhiza orcuttiiOrcutt's woody-aster            5
32BORCryptantha angustifolianarrow-leaved cryptantha        540999999
33BORCryptantha barbigerabearded cryptantha         11 30
34BORCryptantha costataribbed cryptantha           1 
35BORCryptantha maritimaGuadalupe cryptantha            99
36BORCryptantha micranthapurple-root cryptantha         5  5
37BORCryptantha pterocaryawing-nut cryptantha          1  
38BORPectocarya heterocarpachuckwalla pectocarya          29950
39BORPectocarya platycarpabroad-fruited combseed          99150
40BORPectocarya recurvatacurvenut combseed     1       
41BORTiquilia plicataplicate coldenia           1 
42BRABrassica tournefortii*Asian mustard    20  102099999999
43BRADescurainia pinnatawestern tansy-mustard         10   
44BRADithyrea californicaspectacle-pod        2099993099
45BRAGuillenia lasiophyllaCalifornia mustard        1   2
46BRALepidium lasiocarpum var. lasiocarpumhairy-podded pepper-grass         3101050
47BRASisymbrium irio*London rocket         3099220
48BRAStreptanthella longirostrislongbeak streptanthella         2020  
49CACMammillaria dioicaCalifornia fish-hook cactus      111103  
50CAPIsomeris arboreabladderpod   99 29999991010  
51CARAchyronychia cooperifrost mat          2  
52CHEAtriplex hymenelytradesert holly    20      11
53CHEChenopodium murale*nettle-leaved goosefoot         520  
54EUPChamaesyce polycarpasmall-seeded spurge   5   1555 20
55EUPCroton californicusCalifornia croton          5  
56EUPDitaxis lanceolatanarrowleaf ditaxis  22 32129950  
57EUPEuphorbia erianthabeetle spurge         2   
58EUPStillingia linearifolialinear-leaved stillingia        211  
59EUPStillingia spinulosaannual stillingia           1 
60FABAstragalus lentiginosus var. borreganusBorrego milk-vetch    1      10 
61FABCercidium floridum ssp. floridumblue palo verde             
62FABLotus rigidusdesert lotus   1  151031  
63FABLotus strigosusstrigose lotus            50
64FABLupinus arizonicusArizona lupine         1020 99
65FABMarina parryiParry's marina   1         
66FABPsorothamnus emoryiEmory's indigo-bush    11 1   1 
67FABPsorothamnus schottiiindigo bush         1   
68FOUFouquieria splendens ssp. splendensocotillo371010355112010520
69GERErodium cicutarium*redstem filaree      1 59999  
70HYDPhacelia crenulata var. ambiguaheliotrope phacelia           299
71HYDPhacelia crenulata var. minutifloralittle-flowered heliotrope phacelia           101
72HYDPhacelia distanscommon phacelia     3  109999  
73KRAKrameria grayiwhite rhatany            1
74LAMHyptis emoryidesert-lavender 1230 2099999950501010
75LAMSalvia eremostachyadesert sage      111    
76NYCAbronia villosa var. villosahairy sand-verbena        130999999
77NYCAllionia incarnatatrailing four o'clock          1  
78NYCMirabilis bigelovii var. retrorsawishbone plant         510 1
79ONACamissonia californicaCalifornia suncup            20
80ONACamissonia claviformis ssp. peirsoniibrown-eyed primrose        1030999999
81ONACamissonia pallida ssp. pallidapale sun-cup        111  
82ONAOenothera deltoides ssp. deltoidesdune primrose         202099 
83PAPEschscholzia minutiflora ssp. minutiflorasmall-flowered poppy     3  203030 99
84PAPEschscholzia parishiiParish's poppy        1230 20
85PLAPlantago ovatadesert plantain          59999
86POLGilia stellatastar gilia            1
87POLEriogonum deflexum var. deflexumflat-topped buckwheat             
88POLEriogonum inflatumdesert trumpet111 105  1 1 2
89POLEriogonum thomasiiThomas' buckwheat           15
90POLEriogonum wrightii var. nodosumWright's buckwheat3030302  105122  
91PORCalandrinia ambiguadesert red maids           52
92RESOligomeris linifolianarrowleaf oligomeris           30 
93ROSPrunus fremontiidesert apricot 1      20    
94RUTThamnosma montanaturpentine broom   1 122 21  
95SCRMimulus bigelovii var. bigeloviiBigelow's monkeyflower         5   
96SIMSimmondsia chinensisjojoba         22  
97SOLDatura wrightiisacred datura         11  
98SOLLycium andersoniiAnderson's desert-thorn     2  1 3  
99SOLLycium brevipes var. brevipesdesert-thorn     10 1     
100SOLLycium fremontiiFremont box-thorn          5  
101SOLNicotiana obtusifoliadesert tobacco    42 1 33  
102SOLPhysalis crassifoliathick-leaved ground cherry     11 2 2  
103VISPhoradendron californicumdesert mistletoe      1131  1
104ZYGFagonia laevisCalifornia fagonia        3205  
105ZYGLarrea tridentatacreosote bush   21 11223220
106LILHesperocallis undulatadesert lily           502
107POAAristida purpureapurple three-awn        2    
108POACynodon dactylon*Bermuda grass      1      
109POAPennisetum setaceum*fountain grass   1  11222  
110POAPleuraphis rigidabig galleta     3  1210 30
111POASchismus barbatus*Mediterranean schismus       110152099

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 (link didn't work on 9 February 2009)

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.
Commercial rights reserved. Permission is granted to reproduce any or all of this page for individual or non-profit institutional internal use as long as credit is given to me at this source:
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Updated 27 February 2009.