Matelea parvifolia, spearleaf

Fig. 1. Left: Picture showing twining stem, opposite spear-shaped leaves, and the chocolate-brown flower. Right: Closeup of flower. Pictures taken by Tom Chester on 3 December 2010 from the "Salazaria Plateau" west of Yaqui Peak. Click on the pictures for larger versions.

Table of Contents

Geographic Distribution
Elevation Analysis
List of Locations
Discovery Dates
Leaderboard for discoverers of Matelea Locations
Taxonomic History


Matelea parvifolia, spearleaf, is one of the rarest plant species in the Borrego Desert. In five years of surveys, from 2005 to 2010, we found a grand total of eight plants in six locations! The numbers started climbing when we began botanizing its home in the Borrego Desert, in the Plum Canyon area and Smuggler Canyon area. But even after over 400 surveys, the total number of plants found is just 142, from a total of 43 separate locations. Those 43 locations are quite clustered, making up only 11 areas after application of the clustering algorithm used by the Consortium of California Herbaria.

Although this species is rare in the Borrego Desert, it is a widespread species. It primarily lives in the southwestern quarter of Arizona, extending to our area on the west, northern Baja on the southwest, and just barely into mainland Mexico, New Mexico and Texas.

The major difficulty in spotting this species is that it is nearly invisible, even at full bloom, primarily because it is normally a short twining vine growing inconspicuously on a bigger plant. Fig. 2 shows some typical appearances of Matelea plants on different support plants. Two of the four Matelea plants in Fig. 2 are in full bloom!

Photograph by Tom Chester, Pictograph Trail, 27 December 2013

Photograph by Tom Chester, the "Salazaria Plateau" west of Yaqui Peak, 3 December 2010

Photograph by Tom Chester, Hill south of parking area at entrance to Plum Canyon, 12 December 2012

Photograph by Tom Chester, PCT north of Scissors Crossing, 6 January 2012

More photographs of these plants, including close-ups, are given below.

Matelea doesn't seem to care for the most part what plant it gets established under, and then uses as support. The most common in our experience is a small jojoba plant, typically 2-3 feet high. The tallest Matelea plant we've ever seen was seven feet tall twining around an ocotillo stem. The happiest plant we ever saw was growing around a barrel cactus. Other support plants include Ambrosia dumosa, Ephedra aspera, and dead plants that could no longer be securely identified. One voucher said it was growing on a cholla. A support plant is not a necessity; we've seen Matelea growing out of cracks in boulders, and from the ground at the base of boulders.

A special skill is needed to be able to find Matelea plants, which is why this page gives a Leaderboard for discoverers of Matelea Locations.

However, despite the difficulty in finding this species, it seems to be truly rare in our area. There was one voucher of it from Glorietta Canyon from 1996 that we were never able to relocate, despite 12 days of field surveys there, including two in which the only goal of the survey was to look for Matelea, by people who were familiar with Matelea and good detectors of it. That voucher was of a plant growing at the base of a cholla, which would have been easily found at the time of year we did our surveys.

Although we never found it in our surveys, Mary Jo Churchwell came across a specimen there growing in a Hyptis emoryi while collecting in that area for the San Diego County Plant Atlas. We immediately went to see it. Her location was not covered by any of our 12 days of surveys, although we surveyed within 300 feet of that location previously! We can confidently say that Matelea is exceedingly rare in the Glorietta Canyon area. (There were a number of chollas at that location, so it is possible this is the location of the 1996 vouchers, and the plant extant on the cholla was no longer alive.)


The analysis on this page discusses only the 43 observations from our surveys as of 17 January 2014. The table may have been updated with later observations.

Voucher information has not been added to this page yet. We'll add information throughout this page from vouchers in the future, but here is a quick summary of the voucher information.

One of our locations was in our surveys only because Mary Jo Churchwell told us about coming across and vouchering this species from Glorietta Canyon, and giving us a precise GPS location.

There are a total of seven different vouchered locations, including the one from Mary Jo Churchwell. Two other of those seven voucher locations are also the same as our locations:

The other voucher locations are from:

Geographic Distribution

The geographic distribution of Matelea parvifolia from all of our ABDSP surveys as of 1/17/14 is shown in Fig. 1. See also the clustering version of these points.

Fig. 1. Point locations for all of the 43 locations of Matelea parvifolia from our surveys.

The plot in Fig. 1 is complete for all our (~400?) surveys from 2003 - 2014. Although we have only completed digitizing about one-fourth of all of our surveys, we targeted this species to digitize its points from the surveys not-yet digitized. (See also the map of all digitized locations as of 1/10/14).

Note that Matelea is confined to a fairly narrow longitude range. Most of our locations are from just two places: the Plum Canyon area (10 locations), and the Smuggler Canyon area (8 locations).

Table 1 gives some record locations, such as the highest and lowest elevation locations.

Table 1. Record locations for Matelea

Lowest Elevation1435 feet, Glorietta Canyon
Highest Elevation4670 feet, On the Schad Whale Peak Trail where it crosses Smuggler Canyon
Northernmost San Diego County33.39606° latitude, Box Canyon off Coyote Creek
Southernmost San Diego County32.93113° latitude, Upper Moonlight Canyon, Agua Caliente County Park

See the SEINet distribution map for the distribution of this species in the southwestern U.S. and northern Mexico.


Perhaps the most interesting and unusual characteristic of the distribution of this species is that we have never found more than 14 plants at a single location, and the median number of plants per location is ONE! Fig. 2 shows the number of plants per location as a function of elevation.

Fig. 2. The number of plants per location versus elevation for all of the 43 locations of Matelea parvifolia from our surveys.

This is very unusual for species in the Borrego Desert, which nearly all have at least one location where there are 50 or 99 plants.

Elevation Analysis

Fig. 3 gives a histogram of the number of locations versus elevation.

Fig. 3. Histogram of the number of locations versus elevation from our surveys.

There are approximately a constant number of plants per elevation bin from 1400 to 3800 feet, with only two plants found at higher elevations.

There is no mystery about why the plants suddenly appear above 1400 feet. They like to grow in dry, rocky areas, not in the flat desert floor, and the desert floor extends to about 1000 feet elevation on the west of Borrego Springs. It takes another roughly 400 feet of elevation before its habitat appears in any abundance.

Above about 4000 feet the plant community changes from desert transition to montane, and a lot of desert plants drop out at that elevation.

The full interpretation of this plot can not be done until we make similar plots for all our survey points for comparison. In particular:

In particular, the number of plants at elevations of 3000 to 3800 feet jumped in December 2013 and January 2014 simply because we did a number of surveys at that elevation in Smuggler Canyon, where it seems to live in greatest abundance (see Table 1).

Since we have surveyed a lot of area below 1400 feet without finding Matelea, this species clearly doesn't live below that elevation here. Our highest-elevation location, on the Whale Peak Trail, at 4647 feet, is the highest elevation Matelea known in California. The Jepson Manual Second Edition elevation range of 700-1000 m (2300-3300 feet) is clearly too small, which often happens with species that have few vouchers. Munz 1974 gave it as rare, 2000-3000 ft.

The Vascular Plants of Arizona treatment gives an elevation range of 1500-4500 feet, that essentially exactly matches the range we have observed.

Fig. 4 plots the latitude vs. elevation for all the locations from our surveys.

Fig. 4. Left: a crop of the geographic map on Fig. 1. Right: Latitude vs. elevation for Matelea locations from our surveys. The latitude scale approximately matches that of the map on the left, so that the geographic location of the points can be seen.

The Smuggler Canyon / Whale Peak area is responsible for all the points above 3000 feet.

List of Locations

The complete list of our locations for Matelea is given in Table 2, with a histogram of discovery dates in Fig. 5. The recent large number of discoveries is primarily due to us botanizing where Matelea is most abundant.

Table 2. Complete list of survey locations for Matelea

#DateSurvey AreaElevation (feet)# PlantsDiscoverer
112/23/05California Riding and Hiking Trail - VC up to saddle15201James Dillane
212/23/05California Riding and Hiking Trail - VC up to saddle19902James Dillane
301/03/07Agua Caliente Moonlight Canyon Loop15401James Dillane
412/29/08Henderson Canyon south side14802James Dillane
511/25/09Box Canyon off Coyote Creek26001James Dillane
612/03/10Salazaria Plateau29201James Dillane
705/20/11Pholisma branch of Mine Canyon25402James Dillane
801/06/12PCT north of Scissors Crossing28755Tom Chester or Mike Crouse
902/17/12Vallecito Hills16601Mike Crouse
1002/22/12Agua Caliente to Vallecito16501James Dillane and Mike Crouse
1103/16/12Agua Caliente Upper Moonlight Canyon205014James Dillane
1204/23/12Whale Peak Trail46705Mike Crouse
1312/12/12Plum Canyon17006James Dillane
1412/28/12Canyon to east of Plum Canyon24801Tom Chester / Keir Morse
1512/28/12Canyon to east of Plum Canyon247510Tom Chester / Keir Morse
1612/28/12Canyon to east of Plum Canyon25651Tom Chester / Keir Morse
1701/02/13Plum Canyon29658Tom Chester
1801/02/13Plum Canyon30002Tom Chester
1902/15/13Yaqui Pass nw area16151Tom Chester and Adrienne Ballwey
2002/28/13Glorietta Wash and its Canyon14354Mary Jo Churchwell
2103/22/13Plum Canyon21251Adrienne Ballwey
2203/22/13Plum Canyon21201Adrienne Ballwey
2303/31/13Plum Canyon Kate survey as part of tour20301Kate Harper
2410/13/13Canyon east of Plum Canyon Keir Morse trip23651Keir Morse
2512/15/13Pictograph Trail / Smuggler Canyon Loop30603Angelique Herman
2612/15/13Pictograph Trail / Smuggler Canyon Loop33103Keir Morse
2712/27/13Pictograph Trail / Smuggler Canyon33602Kate Harper
2812/27/13Pictograph Trail / Smuggler Canyon34251Tom Chester
2901/07/14Pictograph Trail / Smuggler Canyon keir morse survey33001Keir Morse
3001/07/14Pictograph Trail / Smuggler Canyon keir morse survey36601Keir Morse
3101/07/14Pictograph Trail / Smuggler Canyon keir morse survey41206Keir Morse
3201/11/14Smuggler Canyon Thymophylla survey31201Tom Chester
3301/11/14Smuggler Canyon Thymophylla survey331511Adrienne Ballwey
3401/11/14Smuggler Canyon Thymophylla survey35209Keir Morse
3501/15/14Smuggler Canyon Thymophylla survey32209Tom Chester
3601/15/14Smuggler Canyon Thymophylla survey34851Tom Chester
3701/15/14Smuggler Canyon Thymophylla survey35151James Dillane
3801/15/14Smuggler Canyon Thymophylla survey35608Tom Chester
3901/15/14Smuggler Canyon Thymophylla survey32201Kate Harper
4001/15/14Smuggler Canyon Thymophylla survey32752Kate Harper
4101/15/14Smuggler Canyon Thymophylla survey32954Kate Harper
4201/15/14Smuggler Canyon Thymophylla survey34001Kate Harper
4301/15/14Smuggler Canyon Thymophylla survey35604Kate Harper
4401/23/14Whale Peak Trail42351Kate Harper

Discovery Dates

Fig. 5. Histogram of the discovery dates for Matelea locations. The recent large number of discoveries is primarily due to us botanizing where Matelea is most abundant.

The discoverer is called out separately in Table 2, because sometimes this species is extremely hard to see. Table 3 gives the leaderboard for those with the sharpest Matelea detectors. When two people jointly discovered a given location, each was given one half the credit.

Leaderboard for discoverers of Matelea Locations

Table 3. Leaderboard for discoverers of Matelea Locations

# Locations discoveredDiscoverer
10.5James Dillane
9.5Tom Chester
8.0Kate Harper
7.5Keir Morse
3.5Adrienne Ballwey
3.0Mike Crouse
1.0Mary Jo Churchwell
1.0Angelique Herman


From Plum Canyon, 12 December 2012, of a plant twining around stems of a Simmondsia chinensis, jojoba and a dead or dormant branch of Ambrosia dumosa, burroweed, that is sticking out of the jojoba. It is growing near the top of an exposed sparsely-vegetated very small hill/ridge just south of SR78 with sand andexposed rocks on the surface.

From the PCT north of Scissors Crossing, 6 January 2012, of a plant growing around a Ferocactus cylindraceus, barrel cactus, on a south-facing dry slope amidst broken rock.

From Mine Canyon, 20 May 2011, of a plant growing out in the open, from a crack at the base of a boulder in a shaded canyon bottom.

From the "Salazaria Plateau" west of Yaqui Peak, 3 December 2010, of a plant growing in an Ephedra in an open area with clay soil amidst scattered small rocks.

Taxonomic History

This section contains only some tidbits of info so far, and has not yet been written up in a coherent way.

Gonolobus parvifolius Torr. Rept. Bot. Mex. Bound. Survy. 166, 1859.

Gonolobus hastulatus A. Gray, Proc. Amer. Acad. 12:78, 1877.

Vincetoxicum hastulatum (A. Gray) Heller, Muhlenbergia 1:2. 1900

Gonolobus californicus Jepson, Man. 771. 1925.

Listed as "Gonolobus(?) parvifolius (n. sp.), from Sides of hills, canon of the Rio Grande, below Mt. Carmel, October; Parry. Mountain near the Limpia, western Texas; Wright. Corolla dull yellow, (brown when dry).

The type specimen of Gonolobus californicus is from a collection by T.S. Brandegee. He collected it twice, in "c. 1895" and on apr 6, 1901, with the locality given as "Ironwood Well" which is now known as Yaqui Well. there is no other information on the label.

One of these vouchers is the type specimen for Jepson's name. Jepson described it as a new species in his 1925 manual, as Gonolobus californicus. Jepson states:

Greek gonia, angle, and lobos, pod, one of the early species with angled fruits.

In 1941, Woodson published a monograph on the North American Asclepiadaceae, and give this species the name Matelea parvifolia.

The name Matelea for the genus was given in 1775, in Aubl. Fl. Guian. 1:277. t.109.

Other things to add to this page:

jaeger says vincetoxicum means "poison conqueror" because of its supposed antidotal powers. take a look at the cartoon face on the sticky note at top on this voucher image:

Confusion of name with Matelea parviflora.

We thank Jane Strong for comments on this manuscript.

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Copyright © 2013-2014 by James Dillane, Tom Chester, Kate Harper, Keir Morse, Adrienne Ballwey, Mike Crouse, Mary Jo Churchwell and Angelique Herman.
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 14 February 2014