The transition between Opuntia parryi and O. ganderi along Highway S2 in San Diego County: Data

This page contains the detailed description of the locations where specimens were measured, and the raw data from the investigation described here.

The 14 locations at which data were taken are given in the following table. The milepost mileage was calculated from my car odometer reading, calibrated to three of the mileposts along the road. The mileposts begin at 0 at the northern end of S2, at its intersection with SR79, and increase to the south. Note that Earthquake Valley has been recently renamed Shelter Valley.

Milepost	Description of Location
10.3	San Felipe Valley, north end near springs
12.1	San Felipe Valley, just north of middle
14.3	San Felipe Valley, just south of middle
16.1	San Felipe Valley, just north of Scissors Crossing
17.1	Scissors Crossing
18.0	Earthquake Valley, just south of Scissors Crossing
19.1	Earthquake Valley, just north of middle
20.2	Earthquake Valley, middle
21.4	Earthquake Valley, just south of middle just inside Anza-Borrego Desert State Park border
22.4	Earthquake Valley, south end near Foot and Walker Pass
23.4	Blair Valley, near Ranger Station site on topo map
25.5	Box Canyon, east end
26.4	Box Canyon, west end
27.8	Mason Valley, ~1 mile south of Oroflamme Canyon Dirt Road

Milepost	Tubercle Length (mm)		Max Stem Segment Length (cm)
	min	max
10.3	24	26	23
10.3	20	28	22
10.3	18	20	39
10.3	22	28	28
10.3	21	22	42
12.1	23	29	24
12.1	20	22	14
12.1	16	21	20
12.1	15	18	17
12.1	21	23	22
14.3	15	20	16
14.3	15	22	21
14.3	30	35	43
14.3	20	26	24
14.3	20	27	30
16.1	14	20	21
16.1	16	27	28
16.1	17	21	21
16.1	14	20	20
16.1	22	25	37
17.1	16	21	29
17.1	20	22	34
17.1	19	20	30
17.1	15	20	22
17.1	19	22	25
18.0	16	20	21
18.0	10	16	24
18.0	13	22	24
18.0	15	22	26
18.0	15	20	19
19.1	20	25	31
19.1	17	19	37
19.1	15	20	34
19.1	15	17	29
19.1	20	21	30
20.2	20	22	23
20.2	18	23	24
20.2	17	21	24
20.2	16	20	33
20.2	16	19	21
21.4	12	18	15
21.4	10	17	18
21.4	15	17	22
21.4	13	17	15
21.4	12	17	22
22.4	10	12	19
22.4	10	15	20
22.4	14	20	19
22.4	17	20	25
22.4	12	15	21
23.4	14	18	19
23.4	20	22	28
23.4	15	20	20
23.4	14	19	18
23.4	16	19	25
25.5	15	19	21
25.5	14	19	25
25.5	10	15	16
25.5	15	18	18
25.5	11	15	15
26.4	17	20	13
26.4	13	15	20
26.4	16	21	14
26.4	17	20	19
26.4	15	20	12
27.8	16	21	14
27.8	13	16	17
27.8	15	20	21
27.8	16	20	24
27.8	12	15	25

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• The transition between Opuntia parryi and O. ganderi along Highway S2 in San Diego County