Geographic Distribution of Arctostaphylos Species in the SGM

Fig. 1 shows the difference between A. parryana and A. patula for the hairs and glands of the nascent inflorescence. We've been confused in the past by observing glints in sunlight from A. parryana, and had called those plants A. parryana gold in the following text from the year 2002. We still don't know what causes those glints, but those plants are solidly A. parryana, since the hairs of the nascent inflorescence looking nothing like the heavily-glandular ones of A. patula.

Fig. 1. Left: A. parryana, showing the white hairs of its nascent inflorescence. Right: A. patula, showing the golden-glandular hairs of its nascent inflorescence. Click on the pictures for larger versions.

Text from 2002:

We have begun a project to map the spatial distribution of the manzanita species in the San Gabriel Mountains. The following plots give the data we have gathered so far.

We have kept separate the few A. parryana specimens that look mostly like A. parryana, but have a few golden-gland-tipped hairs.

It is interesting to compare what we have found so far with the elevation ranges given in Munz and JM (all elevations in feet):

Just for fun, we identified the locations of all A. patula plants along the trail from Dawson Saddle to Throop Peak. Each point in the following plots represents either an individual A. patula specimen along the trail, or all specimens within 0.01-0.02 miles of that point. I.e., the long stretches of trail without any plotted A. patula points do not contain any A. patula specimens along the trail, and closely-spaced A. patula points should usually simply be connected with a straight line, indicating that many specimens are found in those locations.

A. patula distribution along the Dawson Saddle to Throop Peak trail: spatial coordinates (map) and elevation vs. longitude plot.

The following table gives the locations used in the large-scale plots:

patula					
	34.36182	242.1306	-117.8694	6607	ne corner of williamson trailhead parking lot
	34.35683	242.14995	-117.85005	6660	islip saddle parking lot, across the street from the bathroom
	34.36149	242.12782	-117.87218	6720	mp 62.26 near mt. williamson trailhead
	34.35866	242.12402	-117.87598	6730	williamson rock parking lot
	34.34469	242.07995	-117.92005	6750	mt. waterman trailhead (mp 58.02)
	34.3677		242.19996	-117.80004	7956	on dawson saddle trail
	34.36724	242.19782	-117.80218	8083	on dawson saddle trail
	34.36496	242.19646	-117.80354	8169	on dawson saddle trail
	34.36046	242.19496	-117.80504	8373	on dawson saddle trail
	34.35785	242.19749	-117.80251	8483	on dawson saddle trail
	34.3543	242.19809	-117.80191	8671	on dawson saddle trail
	34.35221	242.20388	-117.79612	8887	pct just s of dawson saddle trail
	34.35047	242.20168	-117.79832	9138	throop peak


parryana					
	34.30271	242.4859	-117.5141	3752	parryana begins here, 1.8 miles from beginning of lone pine canyon road at bottom, near sr2
	34.27286	241.9559	-118.0441	4580	Parryana started at Barley Flats/Shortcut Saddle on sr2
	34.39183	241.9187	-118.0813	4930	mill creek summit
	34.32679	241.99573	-118.00427	5280	chilao visitor center
	34.29711	241.97222	-118.02778	5908	Vetter
	34.38222	242.22146	-117.77854	5980	manz trail
	34.34937	241.98509	-118.01491	6162	Hillyer
	34.36685	242.3459	-117.6541	6206	just west of wrightwood on sr2
	34.36495	242.25702	-117.74298	6340	bhmt
	34.37491	242.27923	-117.72077	7250	just west of grassy hollow (we need to double-check this one)
		
glandulosa ssp glaucomollis					
	34.19588	241.97331	-118.02669	2560	cabin site on san olene fire road, near chantry flats
	34.21589	241.87027	-118.12973	3100	approximate position on sunset ridge road, above camp sierra
	34.29532	241.83298	-118.16702	3289	glandulosa and glauca at stop 5 8/5/02 afh
	34.21323	241.97207	-118.02793	3420	approximate position on mt. zion trail
	34.2727		241.84206	-118.15794	3520	the Pines Picnic Area on AFH near Clear Creek

glauca					
	34.25803	241.80802	-118.19198	2940	CCC Ridge on ACH
	34.21699	241.86673	-118.13327	2950	near camp sierra on sunset ridge trail
	34.29886	241.85232	-118.14768	3040	5 glauca at stop 2 8/5/02 afh
	34.29532	241.83298	-118.16702	3289	glandulosa and glauca at stop 5 8/5/02 afh
	34.26666	241.85678	-118.14322	3340	switzers
	34.27908	241.83216	-118.16784	3360	5 glauca at stop 1 8/5/02 afh
	34.30582	242.49638	-117.50362	3667	glauca begins here, 1.0 miles from beginning of lone pine canyon road at bottom, near sr2
	34.30751	242.4724	-117.5276	4045	2.7 miles from beginning of lone pine canyon road at bottom, near sr2
	34.38548	241.90333	-118.09667	4509	only glauca at stop 3 8/5/02 afh
	34.25833	241.89579	-118.10421	4666	Red Box
	34.39156	241.91927	-118.08073	4918	forma eremicola at mill creek summit
	34.38222	242.22146	-117.77854	5980	manz trail
					
gabrielensis					
	34.39183	241.9187	-118.0813	4930	mill creek summit
					
					
parryana with some gold hairs					
	34.34248	242.01542	-117.98458	5840	mp 52.63 near three points
	34.38222	242.22146	-117.77854	5980	manz trail

Go to:

• Field Guide to the San Gabriel Mountains: Natural History: Plants: Keys: Manzanitas: Location
• Field Guide to the San Gabriel Mountains: Natural History: Plants: Unlabeled SGM Links
• Native and Introduced Plants of Southern California