Bloom Reports from the Anza-Borrego Desert: 2018-2019

Fig. 1. Proboscidea althaeifolia, desert unicorn-plant, devil's claw, in bloom and fruit at the parking area for Canyon 41, on 18 November 2018. Photo by Tom Chester. Click on the photo for a larger version.

Fig. 2. Hesperocallis undulata, desert lily, in full bloom in the San Felipe Creek area north of the Buttes Pass Road, on 7 December 2018. Photo by Tom Chester. Click on the photo for a larger version.


The Borrego Desert received widespread rain on 4 to 6 December 2018. Over an inch was recorded everyplace west of Borrego Springs, which is enough to germinate the annuals that will bloom in February and March, and even the desert floor east of Borrego Springs received over a half inch.

Although the vast majority of Anza-Borrego Desert State Park was dry as a bone as of 30 November 2018, a few favored areas received rain from thunderstorms on October 12 and 13, producing good annual germination, and have a number of plants already in bloom. There were well over 50 species of flowering plants in both November and December in the Borrego Badlands and Canyon 41 / Canebrake areas! To the great surprise of many of us, we now have small numbers of desert lilies and cacti blooming in early December (see Ernie Cowan's San Diego Union Tribune column).

In those favored areas, the number of plants in bloom at this time of year is the best since 2013-2014, in the top two years out of the last decade for blooms in the late fall. See Number of Species and Plants in Bloom On Each Trip for a comparison of this year with previous years, and the summary table below.

In those favored areas, many plant species grew amazingly quickly from the heat and still-strong October / early November sun in the last month. Nearly all the ocotillos in those areas were wearing their coats of green leaves in mid-November.

Due primarily to four prolific observers, iNaturalist has become a wonderful resource to get almost daily updates on what is blooming in the Anza-Borrego Desert. Click on "Filters" and select a date range to see the observations from that period. For example, here are all the observations on 1 December 2018 and later. As of 18 December 2018, 2664 observations were posted in those eighteen days, primarily contributed by Fred Melgert / Carla Hoegen, Don Rideout, Terry Hunefeld, and Birgit Knorr.

The following map shows where plants tagged as blooming have been photographed at iNat from 1 to 18 December 2018 (Tom went through all those iNat observations for nine of the most-frequently observed species, the ones listed in Table 1, and flagged all their observations for ones in bloom):

Fig. 1. Number of iNaturalist observations tagged as blooming plants from 1 to 18 December 2018. The Berkeley clustering algorithm grouped those observations into clusters, with the number of observations given in the circle. Yellow circles have 11 to 73 observations; blue circles have fewer than 10 observations.

The hotspots are in the San Felipe Creek area between the Borrego Badlands and Borrego Mountain, with 73 observations of blooming plants along the Creek area, and the Canyon 41 / Canebrake area, also with 73 observations of blooming plants. Although there are of course some observational biases with the iNat observations, such as non-uniform coverage, non-uniform tagging of plants as being in bloom except for those nine species, multiple observations of the same plant, the results show clearly where the hotspots are.

The most common blooming species at iNat from 1 to 18 December 2018 are given in Table 1:

Table 1.

#iNat observations
of blooming plants
48Abronia villosa
31Chylismia claviformis
25Pectis papposa
22Encelia frutescens
19Geraea canescens
19Ferocactus cylindraceus
15Dithyrea californica
13Encelia farinosa
11Hesperocallis undulata

The numbers mostly reflect what we have seen. Abronia and Chylismia are far and away the most frequently-observed species in bloom. However, Hesperocallis is over-estimated since a number of the observations are of the same plant in bloom by different people.

Interestingly, few plants of Erodium cicutarium have germinated, probably since it needs cooler temperatures to germinate.

Comparison of this year's Fall bloom to that of previous years

#pls#speciesseasonline color

The table is in declining order by # plants in bloom, where each species contributes a maximum of 99 plants. The current bloom is the second best in that category, and the second best in the average number of species in bloom.

The line color refers to the plots in Number of Species and Plants in Bloom On Each Trip.

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

Anza-Borrego Wildflowers Bloom Report by Fred Melgert and Carla Hoegen, often with daily wildflower updates.

iNaturalist observations in the Borrego Desert since 1 December 2018 (click on "Filters" to change the dates)

Wildflower Updates from the Anza-Borrego Desert Natural History Association.

Anza-Borrego Desert State Park official site, with wildflower information on it. Click on the link near the top with the word Update, which might be updated weekly.

DesertUSA Anza-Borrego Desert State Park Wildflower Reports

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

Theodore Payne Wildflower Hotline (Reports begin the first Friday in March)

Go to:

Copyright © 2008-2018 by Tom Chester, Fred Melgert, Carla Hoegen, Nancy Accola, Don Rideout, Kate Harper, and Birgit Knorr.
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 us at this source:
Comments and feedback: Tom Chester
Updated 20 December 2018