Identification of Purshia Subintegra (Rosaceae)
Great Basin Naturalist
Volume 54 Number 3 Article 7
8-29-1994
Identification of Purshia subintegra (Rosaceae)
Frank W. Reichenbacher Southwestern Field Biologists, Tucson, Arizona
Follow this and additional works at: https://scholarsarchive.byu.edu/gbn
Recommended Citation Reichenbacher, Frank W. (1994) "Identification of Purshia subintegra (Rosaceae)," Great Basin Naturalist: Vol. 54 : No. 3 , Article 7. Available at: https://scholarsarchive.byu.edu/gbn/vol54/iss3/7
This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 54(3), © 1994, pp. 256--271
IDENTIFICATION OF PURSHIA SUBINTEGRA (ROSACEAE)
Frank W Reichenbacher1
ABSTRACT.-Populations ofPurshia in central Arizona are intermediate in some characters between Purshia subinte gra, an endangered species, and Purshia stansburiana, the common cliffrose. These intermediates may represent forms derived from a history ofhybridization and introgression between the putative parent species. Morphological data were obtained from 216 pressed specimens of P. suhintegra, P. stlmsburiana, and introgressed forms. Over 50 separate dis criminant function analyses (DFA) and principal components analyses (PCA) were run on numerous combinations of raw and log"transformed data. The best variable suite, providing the clearest discrimination between groups, used log transformed data on 15 morphological characters, but DFA post-hoc identifications were 90-100% correct with only 7 characters using raw data. DFA distinguished four separate nodes ofvariation. Two groups consisting of 122 P. subinte gra and 29 P. stansburiana were easily discriminated in DFA and were distinguished in PCA as well. Introgressed forms were consistently identified in two much less well"defined groups of 46 and 19 specimens. Introgressed forms are not intermediate between the two supposed parents in some characters, appearing most similar to P. stansburiana in most measured characteristics. Principal distinguishing characteristics ofthe four groups are as follows: P. subintegra-usual ly eglandular, has 0-2 leaf lobes and short hypanthia-pedicelsj P. stansburiana-always abundantly glandular, has 4 leaf lobes and short hypanthia-pedicelsj the introgressed form "Tonto" is usually eglandular, has 4 leaflobes and long hypan thia"pedicelsj the introgressed form "Verde" is usually glandular, has 4 leaf lobes and slightly shorter hypanthia-pedicels.
Key words: Purshia subintegra, Purshia stansburiana, Arizona cUffrose, clijfrose, endangered species, morphometries, introgression, taxonomy,
PUTshia subintegra (Kearney) Henrickson Barbara G. Phillips' 1984 discovery of the (Arizona cliffrose) is protected under federal fourth locality for P. subintegra near Horseshoe law as an endangered species (USFWS 1984). Dam along the lower Verde River. For a federally endangered species like P. At the four locations cited above, PUTshia subintegra it is important, indeed vital, to know subintegra is restricted to outcrops of Tertiary the taxonomic identity of every individual deposits of limy lacustrine rock formations plant in a given population because the protec (Anderson 1986). Soils derived from these tive measures of the Endangered Species Act ancient lake basin rocks are characterized by are available to species (including forms that low nitrogen and phosphorus levels, which exhibit characteristics of introgression with limit, or preclude, typically Sonoran Desert other species), but not to their early generation species that are common on nearby sites with hybrids. soils derived from igneous and metamorphic PUTshia subintegra is found in four widely rocks (Anderson 1986). PUTshia subintegra is a scattered locations from northwestern to species of the northern and eastern perimeter southeastern Arizona (Table 1, Fig. 1). The first of the Sonoran Desert; all four sites supporting collection was made by Darrow and Benson in the species are at or below 1000 m elevation. 1938 (Kearney 1943, Schaack 1987a) near Purshia stansburiana, the common cliffrose Burro Creek in Mohave County, Arizona. A of the Southwest, is not a Sonoran Desert second population was documented in a col species and consequently is not sympatric lection by Pinkava, Keil, and Lehto in 1968 with P. subintegra at three ofthe four P. subin (Pinkava et al. 1970) almost 300 km from tegra sites known. In the Verde River Valley of Burro Creek, near Bylas in Graham County, eastern Yavapai County, Arizona, the highest Arizona. Anderson (1986) found a third popu elevation P. subintegra site, the two species lation on bluffs overlooking the upper Verde occur in close enough proximity that gene River near the town of Cottonwood (referred exchange may occur, at least occasionally. to as the Verde Valley area) and reported on Scattered populations and individuals of
lSouthwestern Field Biologists, 8230 East Broadway Boulevard, Suite W8, TUClion, Ariwna 85710-4002.
256 1994] IDENTIFICATION OF PURSHIA SUBINTEGRA 257
TABLE 1. Locations of Purshia spp, collections sampled in multivariate morphometric analysis; 216 specimens collected for morphological analysis in Arizona.
Region and Letter Elev. collection site N County designation (m) Biotic community Substrate Purshia subintegra I. ByJa, 20 Graham A 850 Sonoran desertscrub Tertiary lacustrine 2. Burro Creek 20 Mohave B 790 Sonoran desertscrub Tertiary lacustrine 3. Horseshoe Lake 42 Maricopa C 640 Sonoran desertscrub Tertiary lacustrine 4. Verde Valley 8 Yavapai D 1025 Semidesert grassland Verde Formation 5. Verde Valley 24 Yavapai E 1050 Semidesert grassland Verde Formation 6. Verde Valley 8 Yavapai F 1065 Semidesert grassland Verde Formation
''Verde'' Verde Valley 7. DK Wen Rd. 3 Yavapai a 1185 Semidesert grassland Verde Formation 8. Seventeen Tank Rd. 6 Yavapai b 1020 Semidesert grassland Verde Formation 9. Mesa Blanca 3 Yavapai c 1210 Semidesert grassland Verde Formation 10. DK Wen Rd. I Yavapai d 1175 Semidesert grassland Verde Formation II. DK Wen Rd. 3 Yavapai e 1155 Semidesert grassland Verde Formation 12. Seventeen Tank Rd. 3 Yavapai f 1035 Semidesert grassland Verde Formation 13. Cottonwood Hwy. I Yavapai g 1030 Semidesert grassland Verde Formation 14. Cornville 2 Yavapai b 1110 Semidesert grassland Verde Formation 15. Black Mtn. Rd. 6 Yavapai i 1385 Pinon-juniper woodland Supai Formation 16. ebeny Rd. 3 Yavapai J 1070 Semidesert grassland Verde Formation 17. Cbony Rd. 3 Yavapai k 1230 Interior chaparral Verde Formation 18. Cbeny Rd. 6 Yavapai I 1270 Interior chaparral Verde Formation 19. Cbeny Rd. 6 Yavapai m 1341 Interior chaparral Verde Formation
"Tonto" Verde Valley 20. Camp Verde 2 Yavapai n 990 Interior chaparral Verde Formation
South ofGlobe 21. Dripping Springs Rd. 6 Gila 0 990 Semidesert grassland Limestone?
Tonto Basin 22. Pinal Creek 3 Gila P 944 Semidesert grassland Tertiary lacustrine 23. Punkin Center 6 Gila q 725 Sonoran desertscrub Tertiary lacustrine 24. Beeline Hwy. 2 Gila r 1015 Interior chaparral Tertiary lacustrine
Purshia stansburiana 25. Jerome 16 Yavapai X 1770 Interior chaparral Tertiary basalt 26. Skull Valley 3 Yavapai Y 1270 Semidesert grassland Weathered volcanics 27. Sonoita 10 Santa Cruz Z 1435 Plains grassland Quaternary alluvium
Purshia in central Arizona exhibit what appear Related Taxa to be intermediate characteristics between P. The systematics ofPurshia is under investi subintegra and P. stansburiana. Numerous botanists (Schaack and Morefield 1985, gation by Dr. James Henrickson for the Schaack 1987a, 1987b, Anderson 1986, 1993, upcoming Chihuahuan Desert Flora and the Henrickson personal communication 1988) revised Arizona Flora. Henrickson (1986) pub have assumed that intermediate forms arose lished a brief note recombining species previ from past hybridization and subsequent intro ously placed in Cowania to Purshia, a move gression with one or both of P. suhintegra and generally agreed upon by botanists. Thns, the P. stansburiana, and that hybridization and genus Purshia now consists of seven species: introgression may still be occurring in some Purshia ericifolia (Torr. ex Gray) Henrickson, P. locations. Throughout this paper the term glandulosa (Curran), P. mexicana (D. Don) "introgressed form," recognizing that the origin Henrickson, P. plicata (0. Don in Sweet) Hen of the intermediates is still unclear, is applied rickson, P. stansburiana (Torr. in Stansb.) Hen to forms that are intermediate in some charac rickson, P. subintegra (Kearney) Henrickson, ters between P. subintegra and P. stansburiana. and P. tridentata (Pursh) DC. Although the 258 GREAT BASIN NATURALIST [Vo!ume54
subintegm, "... restricted to late TertiaJy cal
.-'-'-'-'---'-'-'_'_'_'_ .t>. careous, lacustrine deposits ca. 1&-21 km north I ; west ofBy!as. Graham County, Arizona." I I I , Few botanists have adopted Schaack's tax o P. mbi""gra i \7 P. dan.b",*"".. i onomy, but most recognize that variation is • lntroare_d Fo~ present and concede that it may have resulted I ,I from some form or degree of past hybridiza i, tion or introgression involving P. subintegra , and P. sronsburiana. 80 Y\l , ,I McArthur et al. (1983) reported n = 9 and ., , 2n = 18 for P. Stlbintegm and P. stallSburiana, •• , respectively. Phillips et a1. (1988) used starch •• ,I gel electrophoresis to investigate isozymes at I 14 loci in three populations of Purshia stallS I , buriana and four populations of P. subintegra. The material used in this study was collected by the author and preserved in liquid nitrogen from the same plants that provided dried specimens for this study. Phillips et ali (1988) were unable to discern differential patterns of variability useful in identification oftaxonomic Fig. L Distribution of sampling sites, species, and groups; between-groups similarities ranged introgressed forms. See FIgUre 2 for an e~panded view of Verde Valley. Letters identify sites illustrated in graphs of from 0.925 to 0.992 (Nei [1978J unbiased multivarjate analyses. genetic identity). Filts et a1. (1992) studied PU1'shia subinte gra in Verde Valley, reporting on many impor relationship of P. subintegra to P. stansburiana tant, but heretofore unknown, aspects of the is the subject ofthis study, that of P. subintegra pollination biology of the species. They found to the morphologically similar P. ericifolia is of that flowers may be pollinated anytime in the interest as well. All other P'urshia taxa have first three days after anthesis, the plants are lobed leaves except P. ericifolia. Leaves of P. partially self-compatible, and native and intro ericifolia are about 6 mm long. simple, acute, duced bees are primary pollinators. Reciprocal linear. and eglandular. The species is restricted crossing experiments between P. subintegra to limestone outcrops in the Texas Big Bend and wbat was believed to be P. stansbllriana region. It has been speculated that P. stlbintegra were also conducted by Fills et al. (1992). As may have evolved from some ancient series of is discussed in the concluding section of this crosses and backcrosses involving P. ef'icijolia report, plants from which the P. stansbllriana and some other Ptlrshia, perhaps P. stansburi was taken are actually introgressed forms. ana (McArthur et a1. 1983). Phylogenetic The purpose of this study was to analyze investigation of the whole genus in relation to morphological character variation in species of closely related genera such as Fallugia would purshia in order to identil» the range of mor be valuable in interpreting P. Stlbintegra and phological variation in P. subintegra and to should be the logical next step for future work. develop a means of discriminating between PU7'shia subintegm, an endangered species, Relation to purshia stallSbtlriana and other non-endangered Purshia taxa with Schaack (1987a, 1987b) suggested that the which P. subintegm is most likely to be con basionym P. subintegm was based on material fused. This study was undertaken solely to ofhybrid origin. resulting from past hybridiza address the need ofnatural resource managers tion of P. stansburiana and a previously to have a means ofdetermining which individ unnamed central Arizona Purshia. He conse uals and populations of Purshia are protected quently published a new species name, under the Endangered Species Act. The Purshia pinkavae Schaack, to include a very methods used in this study were carefully cho pure concept of what had been included in P. sen to obtain this result. 1994] IDENTIFICATION OF PURSHIA SUBINTEGRA 259
METHODS mens were also employed. Table 2 shows the character palette developed for the morpho A total of 216 Purshia plants were sampled metric analysis. The list ofcharacters indicates at 27 widely scattered sites from southeastern that a mix ofbinary, categorical, and continuous to northwestern Arizona for measurement and data was used. This was taken into account in analysis of morphometric characters (Fig. 1). subsequent statistical analyses. All measure Much attention was given to sampling Purshia ments and counts were made under a binocu in Verde Valley, the only location where it is lar dissecting microscope with a micrometer believed P. subintegra and P. stansburiaoo are disk or electronic calipers. Scoring procedures in close enough proximity that gene exchange are described in Table 2. might currently be occurring. It was hoped SYSTAT version 4.0 was used to subject the that if hybridization were occurring between data to more than 50 separate discriminant the two taxa, it would be possible to isolate function analyses (DFA) and principal compo characters useful in discriminating between P. nents analyses (PCA) to identify morphologi sul,inlegra, P. stansburiana, and the introgressed cal groups • 1;)<---, - • , "/' ,~ -/'/ ~ 1--"111-:-' • CJ - ~._,... 8'" g' z z :; c: THE IDENTITY OF PURSHIA SUBINTEGRA E ~ Distribution of Specl" and lntrogreased Forma In the Verde Velley Y8v8p1ll -.d Cocontno CountIes Arizona ,/ ,)' " ".'0fI"'" For-. Pt.nhifIsUrJsburiM,a x Jerome \ " -V.... j, k, I, '" eMlry ANd eo d.. OK W.1l ~ Purahia subinteQ" (I~. i BlIck Mln. ReAd O. E, F Verde Valley .,. J(\! c 101_ et.nca • II ConMll. / o WlOilWOCCl~. b.l s-w_Tn Aolld - G:nto' ~ hdiogrHMd For. So "Tonto' Q 2CfO - n Clmp Verde METERS ~ ~ Fig. 2. Distribution ofsampling sites. species. and introgressed fomlS in Verde Valley, Yavapai Co., Arizona. 1994] IDENTIFICATION OF PURSHIA SUBINTEGRA 261 TABLE 2. Characters measured for analysis of character variation in Purshia stansburianll. introgressed fonns, and Purshia subimegra. Descriptions of the character measurements used in multivariate analyses and acronyms (in paren theses) used as variable labels in Tables 4 and 5. Most hypanthia-pedicel, petal. sepal, pistil, and stamen measurements and counts were from the same five flowers from each plant. 1. Leaf pubescence. (LEfPUB) The adaxial surface were measured under a binocular dissectin~ ofPurshia leaves is densely tomentose, though the microscope using a micrometer disk or electronic midvein is often bare. The abaxial surface ranges calipers. The length/Width ratio was also entered from completely glabrous to completely obscured as a character variable (HYPRA1). by long arachnoid hairs. Twenty leaves from each of the 216 plant specimens were scored on an 8-10. Sepal dimensions. (SEPLGTH, SEPWDTH) All iode:t of leaf pube.~nce density. Only the dorsal sepals (usually 5) frum five flowers from each of (abaxial) surface was scored. The scale ranged the 216 plants were dissected and measured from I (completely to nearly completely glabrous) under a microscope using a micrometer disk or to 5 (densely pubescent). electronic calipers. Ma.ximum (basal) width and length of t.he sepals were recorded. The length! 2. Leaf glands. (LEAFGLAN) Ten leaves from each width ratio was also entered as a character vari of the 216 plants were examined and scored for able (SEPRA1j. presence or absence of impressed-punctate glands. 11-13. Petal dimensions. (PETLGTH. PElWDTH) All petals (usually 5) from five Dowers from each of 3. Hypanthium-pedicel glands. (HYPGLAN) Five the 216 plants were dissected and measured hypanthia (with pedicels) from each plant were under a microscope using a micrometer disk or examined and scored for presence or absence of electronic calipers. Maximum width and length of stipitate glands. the petals were recorded. The lengthlwidth mHo was also entered as a character variable (PETRAT). 4. Leaf Jobes. (LOBES) The number of lobes on each of 20 leaves from each of tJ)e 216 plants was 14. Pistil number. (PSLSFLR) Flowers normally con counted, The leaf tip was not counted. Lobes var- tained 2-4 pistils. Aborted pistils were easily dis ied in distinctness, i.e., from much longer than tinguished by their small size « 1.25 mm long) wide to mere bumps on the edge ofthe leaf. Even and brown 10 dark brown color. Viable pistils were the most minOt lobes were scored. Figure 3 illus- pale yellow with silvery-white aehene hairs and trates variation in leaf lobing among P. subintegra, were nearly always longer than 1.25 mm. The the "Tonto" and "Verde" introgressed forms, and tolal number of pistils per flower was counted on P. stansburiatta, and provides an example of lobe each of the 216 specimens, as well as the number scoring. ofviable and aborted pistils. 5-7. HypanLhium-pedicel dimensions. (HYPLGTH. IS. Number of stamens. (STMNS) Stamens were HYPWDTH) Length and maximum width of five counted. in five flowers from each of216 plant~. hypanthia-pedicels from each of the 216 plants Table 3 lists mean values and standard Principal Cnmponents Analysis errors obtained for each of the 15 characters Rotated factor scores derived from three included in the analysis for each of the fonr PCAs are listed by character in Table 4 and identified gronps of Pursllia spp. Fignre 4 are graphed in Fignre 5. The first three factor ilInslrates the dislribntion ofvariation in sepal and hypanthinm-pedicel dimensions. Note axes together account for 73--87% of variance that sepal length and width are highly and in the data. Horizontal relationships on the positively correlated among groups, while FACTOR(2)/FACTOR(1) graphs for each hypanlhinm-pedicel width and length are not analysis (x-axis, Figs. 5A-5C) are primarily P. subintegra plants have shorter, narrower based on leaf lohing, while vertical relation sepals, while P. s/ 262 GREAT BASIN NATURALIST [Volume 54 P. "Verde" 444 '13444442433434344 "I'onto" l( ~3.70 4 4 4 4 4 4 4 4 4 4 4 4 4 4344444 l(03.95 t~~~~~V'~~\7' 444443444444242434642444 l(03.70 Fig. 3. Variation in leaf lobing and size in Purshia subintegra, "Verde" and "Tonto" introgressed forms, and Purshia 8tansburiana. Arrays of20 leaves scored for pubescence, gIandularity, and lobing from typical specimens in each group. Number of leaf lobes scored for each leaf and mean score for each plant are shown. P. stansburiana groups (X-Z) are lost among this reason, DFAs were fJIst run on data matri "Verde" introgressed forms (b, c, d, e, f, g, h, i, ces in which groups were assigned according k, I, m), but a careful examination ofthe distri to the 27 collection sites for each plant, rather bution of points along FACTOR(3) (z-axis) than a preconceived notion of the classifica shows thaI, primarily on the basis ofhypanthi tion of each plant. A series of 27-group analy um-pedicel length, P. stansburiana are more ses were run (Figs. 6A, 6D, 6G) using the 15-, similar to each other. P. subintegra and P. stans 7-, and 4-character sets. This clearly showed bt,riana groups (A-F and X-Z, respectively) that the data naturally fall into at least three or are usually closest to each other. Introgressed four groups, depending on how many charac forms (a--r) are more loosely grouped together ters are used. or near P. subintegra or P. stansburiana. Results ofthe 27-group DFAs were used to reclassifY each plant into one of three or four Discriminant Function Analysis groups. Bylas, Burro Creek, Horseshoe Lake, Univariate and multivariate F-tests con and Verde Valley (sites D, E, F) plants were ducted as part of DFA indicated that 14 of 15 classified as P. subintegra. Plants collected characters used were significant at or below from Jerome, Skull Valley, and Sonoita were the .001 level of significance. Sepal length/ placed in P. stansburiana. All other plants were width ratio was the only character that did not placed in "Verde" or "Tonto" introgressed produce a high F-number. This was true of all forms, or were combined together in a single character combinations and a priori grouping group of introgressed forms. Figure 6 illus assumptions. trates results of nine DFA analyses with three Two-dimensional graphical illustrations of character suites, each analyzed on two addi canonical factor scores often used to show tional a priori grouping assumptions. groupings derived from DFA are partially Character suites containing as few as two dependent on initial group assignments. For characters (e.g., hypanthium-pedicel length 1994] IDENTIFICATION OF PURSHIA SUBINTEGRA 263 TABLE 3. Characteristics of 27 groups of sampled Purshta spp. Mean values and standard errors (in parentheses) are listed for 15 measured characters of27 sample sites and 216 specimens. Purshia "Verde'" "Tonto" Pursma Character subintegra stonsburiana Leaf pubescence 2.075 1.538 1.330 1.393 (scal.l-5) (0.052) (0.055) (0.055) (0.091) Leaf lobes 0.721 3.896 3.988 3.734 (count) (0.074) (0.135) (0.109) (0.083) Leaf gland, 0.020 0.883 0.200 1.000 (presence-absence) (0.012) (0.042) (0.083) (0.000) Hypanthium-pedicd glands 0.107 0.891 0.400 1.000 (presence-absence) (0.028) (0.046) (0.112) (0.000) Hypantbium-pedicell.ngth 5.098 9,170 \0,113 6,620 (rom) (0,073) (0,266) (0,674) (0,151) Hypanthium width 2.447 2.154 3.258 2,945 (mm) (0.033) (0.039) (0.115) (0.071) Hypantbium-pediceJ lengthiwidth 2.132 3.591 3.147 2.275 (0.031) (0.086) (0.213) (0.043) Sepal length 3.565 4.050 3.961 4.886 (rom) (0.042) (0.069) (0.150) (0.115) Sepal width 2.818 3.283 3.498 4.295 (mm) (0.031) (0.056) (0.102) (0.089) Sepal lengthiwidtb 1.282 1.248 1.390 \.151 (0.014) (0,018) (0,126) (0.022) Petallengtb 8,494 9,880 \0,678 11,246 (mm) (0,10lJ) (0,164) (0,342) (0,215) Petal width 5,730 8,357 8,289 10.307 (mm) (0,087) (0,219) (0,305) (0,288) Petal lengthiwidth 1.536 \.226 \.311 \.147 (0,201) (0,027) (0,024) (0,022) Stamens 48,582 67,404 66,585 88,961 (count) (0,879) (1,760) (3,245) (4,035) Pistils 3,465 5,364 5,222 5.486 (count) (5,364) (0,088) (0,204) (0,179) and sepal width), and essentially all other com More lightly clustered DFA plots of l'. binations of characters up to the full 15 avail subintegra are taken to indicate less morpho able, consistently produced the same pattern: logical variability in these four populations P. subintegra and P. stansburiana are grouped relative to the other groups, Separate DFAs in distinct clusters, but the P. subintegra cluster and peAs run only on the P. subintegra plants is normally much more cohesive than the indicate that significant variability occurs other, while both introgressed furms are usually within this group, and post-hoc identification loosely grouped in one or two clusters. ofeach plant into one ofthe four P. stlhintegra The best discrimination between groups groups is about 50-90% accurate. In contrast, was obtained using all 15 characters, with a 3 OFAs using only l'. stansburiana and intro group assumption (Fig, 6B), There is virtually gressed forms (i,e" no P. stWintegra) provided poor discrimination betw'een those groups. 00 overlap between groups, except in the case Each DFA produced a set of group mem of collection site a, Table 5 lists canonical load bership prnbabilities for each plant. These ings for each character on each discriminant were used tn create the tables of a priori and function (OF) obtained from DFA, These are predicted memberships shown in Table 6, useful in identifying the characters most These predictions were almost always highly responsible for discriminating on each of the accurate, over 95%. In the 4-character, 4 DFs, In every DFA, leaf glandularily and lob group analysis (Table 6), DFA was only about ing are the highest loading characters on DF I, 80% accurate for the "Verde" and "Tonto' and frequently load highest on the second and groups, but over 95% accurate for identifying third DFs as well, In the 15- and 7-character P. subintegra and P. statlSburiatw. suite OFAs, hypanthium-pedicel length is "Tonto" plants have long hypanthia-pedicels usually the third highest loading character, (mean 10,1 mm) and eglandular leaves, while 264 GREAT BASIN NATURALIST [Volume 54 1.' 17 A B -~ 15 P• .con.burlallQ >- -:z: E 1.0 .. " C " w" ~ • .. l Ito i" " Id Form C "n " Inlrogr .Q'n...... S ed FOI'Dl I 9 .. 0.$ I!!I 'vi C ,1 ~ ..>- .. :z: 7 8l :z: ~ P. e"W"N'1"d :II • " 0.0 ", • 0 2 3 4 • ... 2.5 U 4.' MEAN NO. LOBES/LEAf MUN HVPAHTHIU" WtDTtI (mat) I.' Fig. 4A-C. Plots of key characters used in multivariate e analyses. Mean values for each of the 21 collection sites. Ellipses include .05 and .90 oonfidence intervals about -E bivariate data means for each of the two Purshia spp. and ! ••• two introgressed forms. See Table 1 for list of code.~ iden x 'f tifying each collection site and Table 2 for list of charac ~ ters. Only two eUip~e~ are visible in Figure 4A because P. Jntroerened FOnll d .. 4.' sUmsburWJUJ, sites X, Y, and Z scored exactly 1.0 for all leaf ~ gJandularity samples; thus there was no standard eTror to measure for that group. ill.. ";:I 3.' " 2.' 2.0 2.8 3.0 3.5 •.0 4.5 $.0 '.S MEAN SEPAL WIDTH (film) "Verde" plants have sligbtly shorter bypan DISCUSSION tbia-pedicels (mean 9.2 mm) and glandular punctate leaves. Generally, "Tonlo" plants are Multivariate analysis of character variation found in Gila County, Arizona, on lakebed clearly indicates that the four Purshia subinte deposits around Hooseve!t Lake in Tonto gra populations sampled exhibit a coherent Creek basin. Note that Camp Verde, site n, is syndrome of characters. Although there is included in the "Tonto" introgressed form some variation between populations, the tax despite its location in Verde Valley in close onomy developed by Schaack (1987b) is not proximity to tbe "Verde" introgressed fonn. supported by the analyses. Specimens claimed This assignment resulted from inspection of to be of hybrid origin by Schaack (1987a, previous DFAs and PCAs. Pinal Creek "Tonto" 1987b) from among the type material collected plants (site p) are frequently given the bighest at Burro Creek should be considered to repre probability of belonging to the "Verde" intro sent P. subintegra. It may be speculated that gressed form despite their location far away leaf lobing and leaf and hypaothium-pedicel from any other "Verde" collection site (Fig. 2). glandularity exhibited by these specimens Plants at these collection sites illustrate the arose from a limited exchange ofgenetic infor high degree of variability in phenotypic mation with P. stansburiana during a period of expression ofintrogressed forms. brief proximity in the ranges ofthe two species. 1994J IDENTIFICATION OF PURSHIA SUBINTEGRA 265 TABLE 4. Principal components analysis ofPurshia spp. information with any other Purshia taxon. P showing factor axis loadings resulting from analysis of the subintegra in Verde Valley is restricted to a full set of measured characters and two abbreviated sets. Scores from the first three factor axes are given for each band roughly 1 km wide and 6 km long, paral character set. leling the Verde River east of Cottonwood, 15~character set Factor axis Arizona, which may extend north along a series of bluffs overlooking Verde Valley (col 1 2 3 lection site a). This isolated edaphic relict is LOBES 0.557 0.212 0.221 surrounded by pockets of Purshia plants that STMNS 0.118 0.111 0.045 appear to be intermediate in some characters 0.092 0.107 0.075 PETWDTH between it and stansburiana, which occurs PSLSFLR 0.074 0.088 0.101 P. SEPWDTH 0.041 0.059 0.017 only at elevations above 1500 m. Table 7 pre PETLGTH 0.021 0.043 0.056 sents a simplified chart of ecological and mor SEPLGTH 0.010 0.045 0.025 phological characteristics that may be used to LEAFGLAN 0.085 0.259 0.103 HYPLGTH 0.054 0.050 0.256 distinguish P subintegra, introgressed forms, HYPWDTH 0.010 -0.016 -0.007 and P stansburiana. Generally, P subintegra HYPGLAN 0.076 0.304 0.090 plants have no leaf glands, 0-2 lobes per leaf, PETRAT -0.050 -0.040 -0.015 and hypanthia-pedicels about 5 mm long; P SEPRAT -0.013 -0.019 0.004 LEFPUB -0.057 -0.072 -0.063 stansburiana plants have abundant leaf glands, HYPRAT 0.024 0.035 0.188 at least 3-4 lobes per leaf, and hypanthia % oftotal variance 32.432 22.723 17.367 pedicels about 6.6 mm long; introgressed 7-character set forms leaves are glandular or not, have at least 3-4 lobes per leaf and hypanthia-pedicels LOBES 0.569 0.252 0.185 SEPWDTH 0.044 0.067 0.013 about 9-10 mm long. Approximately 86% of SEPLGTH 0.015 0.055 0.015 leaves of "Verde" forms are glandular, while HYPWDTH 0.006 -0.014 O.oJS only 20% of"Tonto" leaves are glandular. LEAFGLAN 0.086 0.274 0.073 HYPLGTH 0.066 0.081 0.257 "Verde" and "Tonto" plants are rare to un HYPGLAN 0.077 0.316 0.069 common throughout the Verde and Salt River % oftotal variance 43.075 31.713 13.894 basins between 600 and 1500 m elevation. In 4·character set Verde Valley, "Verde" plants are found on the same Verde Formation soils as support Purshia LOBES 0.590 0.177 0.197 LEAFGLAN 0.101 0.166 0.084 subintegra. Collection site i, of "Verde" plants HYPGLAN 0.091 0.302 0.074 from Verde Valley, occurs on sandy reddish HYPLGTH 0.075 0.057 0.263 soils derived from weathered Supai Formation % oftotal variance 50.081 20.615 16.208 sandstones. Some of the "Tonto" collection sites occurred on Quaternary alluvium derived VVhatever gene exchange occurred must have from weathered granites and schists, some occurred many generations ago and did not occurred on limy soils derived from Tertiary sufficiently influence the values taken by lakebed deposits, and some on conglomerates Burro Creek Purshia planls in respect to the composed of volcanic ashes and mudflows. 15 characteristics evaluated here to differenti Most of these sites were characterized by ate these specimens from P. pinkavae repre sparsely vegetated sterile or poor soils. sented by the specimens I collected at Bylas. Fitts et aJ. (1992) attempted to perform re Andersou (1986) reported that the Horse ciprocal crossing experiments involving P. shoe Lake population primarily comprised subintegra and P stansburiana with pollen hybrid and introgressed forms that were in the from what the investigators believed to be P process of being "swamped out" by P stans stansburiana in a dry wash only a few score buriana. It is now clear that all Purshia plants meters from their P. subintegra study subjects in the area are appropriately identified as P at Dead Horse Ranch State Park (about 2 km subintegra and that P. stansburiana is not pres north of Cottonwood), and approximately 3 km ent except perhaps at higher elevations several northwest of Verde Valley P subintegra sites kilometers distant. D, E, and F (Fig. 2). Reciprocal crosses result At Bylas, Burro Creek, and Horseshoe Lake, ed in 50% seed set, compared with 80% for P. subintegra is unlikely to exchange genetic within-species outcrossed flowers and 20% for 266 GREAT BASIN NATURALIST [Volume 54 A B • • • • , L • L• -, -, • -' 15 CHARACTER SET 7 CHARACTER SET c Fig. 5A-C. Three-dimensional plots of mean factor • scores for each of the 27 collection sites of Purshia. spp. and introgressed forms included in the peA on the first • three factor axes. See Table 1 for locations and descrip tions ofsites corresponding to letter codes and Table 4 for , lists ofcharacters used in the three sets. L• -. • -' ~ 4 CHARACTER SET self-pollinated flowers. Seeds appeared nor remains whether reciprocal crossing experi mal and viable, although no attempt has been ments were conducted with pollen from P. made to study viability of the seeds produced stansburiana or «Verde" introgressed fonus. u.s. from reciprocal crosses (V. Tepedino personal Fish and Wildlife Service botanists Sue Rutman communication June 1992). and Bruce Palmer collected four post-reproduc Identity ofthe plants from which P. subinte tive specimens ofPurshia sp. in November 1992 gra pollen was taken is clear, but the question fi'om the same dry wasb used by Fitts et aI. in 1994] IDENTIFICATION OF PURSHIA SUBINTEGRA 267 10 r2-7-G-,o-u-p's,-1-5-C-h-ar'a-et-e-,s-~--'3-G-ro-u-p-s,rl-5-C-h-ar'a-et-e,-s-~--'-4-G-,o-u-psT,-1-5-C-ha-rTa,-'e-,-s-~----;10 5 5 p.SUbin~ P. SUbint~ o a a Introgressed -5 A \(fn B Fonn C "Tonto" -10 1-2-7-G-,a-u-p"'s,-7-Ch-o-ro""-le-rs--+--+3-G-,o-u-P--js,~7-C-h-o-ra-+'-le-,s---t---+-4 -G-'o-u-ps+,-7-C-h-o,-o,+'-e,-s--+--- -10 5 5 N -~ P. subintegra go @ o ~ a -5 Introgressed -5 D c:li n E Form F "Tonto" '--/ -10 1--+----+---+--+--+---+---+---+---+--+---+----1 -10 27 Groups, 4 Cnoraelers 3 Groups, 4 Charaders 4 Groups, 4 Charaelers 5 "Tonto" 5 ~ °0 ~ o P. subintegra ~-; ~ P. stansburiana -5 Introgressed -5 G 'itl n H Fonn I -1 ~1·':0c-----:.5=-----=0c--::-5 --.-c'10C:--_5=--~0 -~5-c--_1LO---5"'::--~0--5"---lllr1 0 FACTOR(1) FACTOR(1) FACTOR(1) Fig. 6A-I. Plots ofmean factor scores for each of the 27 collection sites ofPunhia spp. and introgressed forms includ ed in nine separate DFAs on the first two discriminant functions. Ellipses representing .90 confidence intervals about bivariate data means for each ufthe 27~group analyses (A, D, G), and .90 and .05 confidence interval ellipses for the 3~ (B, E, H), and 4- (G-I) groups ofPurshia spp. and introgressed forms. their pollination studies. Like Fitts et aI., added to the data set used for previous analy Rutman and Palmer identified these speci ses. The four new specimens were classified mens as P. stansburiana, based primarily on through DFA as P. stansburiana or the ''Verde'' glandularity and leaflobing. As already stated, introgressed form, but not as P. suhintegra or I believe there is no P. stansburiana in Verde the "Tonto" introgressed form, depending on Valley; the species is restricted to elevations which a priori grouping assumptions were over 1500 m. The four pressed specimens used. When the four new specimens were were rehydrated and meaningful data were placed in their own group and added to the obtained from hypanthia-pedicels that were 27-group analysis discussed above, they were dried but persisted in place. Two of the speci easily distinguished from P. stansburiana and mens had one or two fresh flowers in anthesis. placed in the "Tonto" introgressed form group, Data collected from these specimens-includ primarily based on hypanthium dimensions. ing leaf glandularity, leaf lobing, hypanthium Whether Fitts et al. (1992) used P. stans glandularity, hypanthium length, hypanthium buriana or plants more representative of what width, sepal length, and sepal width-were should be called an 'introgressed form', their 268 GREAT BASIN NATURALIST [Volume 54 TABLE 5. Canonical within-groups structures obtained by discriminant function analysis ofPurshia spp. Canonicalload~ iugs resulting from analysis of the fun set of measured chm'actcrs and two abbreviated sets. Each character set is sub- jected to analysis under three a priori grouping assumptions: 27 groups (one for each specimen collection site), 3 groups (Pur8hia suhintegra, introgressed forms, P. stansburiana), 4 groups (P. subintegra, introgressecl form "Verde," intro- gressed form "Tonto," P. stansburiana). IS-character set 27-group analysis 3-group analysis 4-group analysis DF I 2 I 2 I 2 LEAFGLAN 0.594 0.444 0.457 0.294 0.609 0.494 HYPGLAN 0.256 0.145 0.338 0.180 0.360 0.233 LEFPUB -!UOI 0.078 -0.196 -0.040 -0.175 -0.008 LOBES 0.500 -0.300 0.632 0.061 0.579 -0.043 HYPLGTH 0.309 -0.552 0.411 -0.314 0.374 -0.439 HYPWDTH 0.030 -0.090 0.057 0.199 0.019 0.094 HYPRAT 0.234 -0.400 0.336 -0.406 0.330 -00444 SEPLGTH 0.154 0.2()2 0.225 0.373 0.207 0.341 SEPWOTH 0.224 0.198 0.340 0.532 0.299 00455 SEPRAT -0.045 -0.056 -0.037 -0.117 -0.040 -0.131 PETLGTH 0.159 0.021 0.255 0.210 0.228 0.145 PETWDTH 0.281 0.107 00428 0.375 0.388 0.315 PETRAT -0.158 0.001 -0.251 -0.122 -0.240 -0.119 PSLSFLR 0.272 -0.059 0.439 0.106 00408 0.048 STMNS 0.264 0.176 0.318 0.385 0.288 0.335 7~character set LEAFGLAN 0.639 0.531 0.533 0.304 0.690 0.498 HYPGLAN 0.276 0.201 0.392 0.180 0.406 0.226 LOBES 0.545 -0.249 0.726 0.003 0.637 -0.118 HYPLGTH 0.341 -0.633 0.461 -0.425 0.403 -0.551 HYPWDTH 0.036 -0.068 0.071 0.234 O.oI5 0.107 SEPLGTH 0.164 0.229 0.269 0.125 0.235 0.369 SEPWDTH 0.241 0.267 0.106 0.604 0.337 00490 4-character set LEAFGLAN 0.651 0.720 0.534 0.602 0.719 -0.612 HYPGLAN 0.281 0.255 0.394 0.358 0.426 -0.260 LOBES 0.565 -0.362 0.730 0.032 0.685 0.289 HYPLGTH 0.357 -0.641 0.466 -0.796 0.425 0.621 experiment indicated a significant potential velutina, and a putative hybrid. Anderson and for gene exchange outside ofE subintegra. Harrison (1979) used morphological data and The introgressed forms, "Verde" and PCA to test Cooperrider's (1957) use of "Tonto," are nearly identical to P. stansburiana Andersons (1949) hybrid index to determine in leaf lobing, leafvestiture, stature, and num the degree of introgression between putative ber of pistils per flower. They are only inter hybrid and putative parent species in Iowa. mediate in leaf and hypanthium-pedicel glan Data collected by Anderson and Harrison in dularity, sepal and petal dimensions, and num Oklahoma showed that, in some characters, ber of stamens per flower. Length and width the hybrid was definitely intermediate, while in of the hypanthium-pedicel in the introgressed other characters the hybrid was more similar fOnTIS are not intermediate between P. subinte to Q. velutina than Q. rrutrilandica. Ordinations gra and P. stansburiana; hypanthia are consis M of data in PCA showed putative hybrids were tently longer and, for most populations, nar clearly more similar to Q velutina. On the sur rower. Inb'ogressed forms do not appear to be face one would expect that putative hybrids closer to P. subintegra in any of the scored or are backcrossing with Q. velutina, but not with measured characters. Cooperrider (1957) and Q rrutrilandica. Anderson and Harrison, point Anderson and Harrison (1979) studied a simi ing out that they can find no ecological reason lar situation in Quercus marilandica, Q. why backcrosses with Q rnarilandica should 19941 IDENTIFICATION OF PURSHlA SUBINTEGRA 269 TABLE 6. Post-hoc classification of cases in groups from discriminant function analysis. A priori classifications are on the left side, predicted group memberships on the top. 216 cases, 15 characters, 3 groups Actual group P. Btansburiaoo rntrogressod form P. subintegra Total P. stansburiona 29 0 0 29 Illtrogressed fonn I 62 2 65 P. subintegra o 0 122 122 Total 30 62 124 216 216 cases, 15 characters, 4 groups Actual group P. stansburiatw "Verde" "Tonto" P. subintegra Total P. stansburiana 28 0 0 0 28 "Verde" 0 44 0 2 46 "Tholo., I 0 19 0 20 P. subiniegra 0 0 0 122 122 Total 29 43 19 124 216 216 cases, 4 characters, 3 groups Actual group P. stanshurialla Introgres:e;ed form R subintegra Total P. stansburi.ana 29 0 0 29 1ntrogressed fonn 13 49 3 65 R subiniegra 0 0 I22 122 Tolal 42 49 12S 216 216 cases, 4 characters, 4. groups Actual group P. stansburiana "Verde" "Tonto" P. subintegra Total P. stansburiana 28 0 0 0 28 "Verde" 9 32 2 3 46 "Tonto" 0 4 16 0 20 P. sumntegro 2 0 0 120 122 Total 39 36 18 123 216 not be just as prevalent as those with Q. vel"ti. sented bere do not indicate which of the sam lUI, argue instead that the problem lies in not pled plants, ifany, represent F I hybrids, properly delineating the range of variation in Results obtained in this study of Purshia putative parents, putative hybrids, and intro indicate that while it is reasonably simple to gressed forms. They found characters with determine what is P. subintegra. it is not non-intermediate dimensions, but in every always possible to distinguish what have been case these were closer to one putative parent referred to as 'inlrogresscd forms' from P. stans than the other and not, as described here for buriana. Results of Anderson and Harrison hypanthium-pedicel dimensions, qnite differ (1979), in a situation similar to that described ent from both putative parents. 'Ibis could be here, might suggest that we consider intro accounted for by several factors including nat gressed forms a part of the natural variation ural variation, heterosis, and linked gene con~ inherent in locally adapted P. stansburiana troIs ofsimple characters. No breeding experi genomes, and not, as has been assumed by ments involVing P. subintegra and P. stansburi many, a result from a predominance of back ana have yet been carried out so that we may crosses with P. stansburiana. Why tJlen are describe the quantitative characteristics of an forms as similar to P. stansburiana, as described actnal hybrid. It has only been assumed so far above, found in such proximity to P. subintegra that a hybrid should possess a morphology at Dead Horse Raoch, and how is it that roughly intennediatc between the parents. P. subintegra in Verde Valley has remained The close proximity of some "Verde" plants to morpbologically distioct despite what appears P. subintegra suggests the opportunity for to be ample opportunity for extensive hy hybridization exists now, although data pre- bridization? 270 GREAT BASIN NATURALIST [Volume 54 TABLE 7. Reliable charclcters useful in discriminating between P. subtntegra, P. staflSburiana, and introgressed forms. Quantities in parentheses are mean values taken from Table 3. Other data are based on author's observations and Anderson (1986). Pursrna. Purshia Character S1.Ibinleg,ra "Verde" "Tonto" stansburiana Dislrihulion 640-1065 m elevation, 1020--1385 m elevation, 725-1015 m elevation, Statewide (except soutb- Ilurthwest ofBylas, Ven::le Valley, near Camp Verde. western quarter), Graham Co.; Horth Yavapai Co. Yavapai Co.; generally above 1500 m of Burro Cr" Mohave Tonto Basin :lud elevation Co.; Horseshoe L., south ofGlobe, Gila Co. Mmicopa and Yavapai cos.; east ofCottonwood, YavapiU Co. Eeo!f>b,'Y Restricted to limey soils Mostly restricted to Limey soils of Various derived from weatJlered limey soils derived from wenthered lakebed lime- Tertiary lakehcd weathered Thrtiary stones; other limestone limestones lakeb~ limestones. fonnations. soils dcrivett oCt,'asionally on Supai &om \lQlcanics and FOrmation sandstones alluvial materials Growth fnrm Shmb, up to 1 m tall, Shrub, 1-2 m tall when Shrub, 1-2, or some- Shmb, 3--5 m tall whon stems widely and mature, widely and times 3 m tall when mature, stems erect. sparingly bram:hing sparingly br.mched mahlTe, widely and branchiug from the from thc base from the base sparingly brunched bare £rom tbe base Lcafshape Entire or 1-2 lobes 3--51ohes (3.7 lobes 3->5 lobe, (4.0 lobes 3--5lohes (3.7 lobes (0.7 lolles per leaf) per leaf per leaf) per leaf) Leafvestiture Vel)' densely pubescent VelY densely pubescent Very densely pubescent Vel)' densely pubescent on lower surface, less on lower surface, less on lower surface, less on lower surface, less puhescent on upper pubescent to bare on pubescent to bare on pubescent to bare on surface upper smface upper sur£"lce upper surface Leal UsuaUy none, rurely Usually 1ot1andular Usually not glandular Ahundantly glandular glandullUily with impTCllscd punctate (86% glandular) (20% glandular) (100% ~Ialldular) glands (2% glandubr) Hypanthia- Short, usually not Long, usually with Long, usually without Short, with abundant pedicels glandular, rnrely with stalked gland.~ (9.2 rom stalked gland.~ (10.1 mm ,talked gland, (6.6 mm stalked glands (5.1 lOm long, 2.2 mm wide. long, 3.2 rom wide, long. 2.9 mm wide. Ion&, 2.4 lOrn wide, 89% glandular) 40% glandular) 100% glandular) 11% glandular) Sepals short and narrow (3.6 L>ng and narrow (4.1 Short aud wide (4.0 lOrn Long and wide (4.9 rom mm long, 2.8 mm wide) lOrn long, 3.3 lOrn wide) long, 3.5 lOrn wide) long. 4.3 mm wide) Petals Short and very narrow LonK and wide (9.9 lOrn L:mlot and wide (10.7 mm Very long and very wide (8 ..'5 rom long, 5.7 rom long, 8.4 lOrn wide) long, 8.2 rom wide) (1l.3 mm long, 10.3 mlO wide) wide) Pistils 3--4 (3.5 per flower) 4--6 (SA per flowor) 4-6 (5.2 per flower) 4-6 (5.5 per flower) Stamens (48.6 per flower) (67.4 per flower) (66.6 per flower) (89.0 per flower) Deciding whether the introgressed forms, for the purpose of determining what is and "Verde" and "Tonto," should be considered as is not to be considered endangered under fed such, Dr, alternatively as manifestations of a erallaw. broader concept of P. stansburiatUl, is not vital o nomenclatural revisions or additions to to the need that prompted this study: namely, the classification of Purshia are proposed; a means of accurately identifying P. 8ubintegra plants reported here as introgressed forms 1994] IDENTIFICATION OF PURSHIA SUBINIEGR4 271 should be regarded as such unless carefully __=-' 1993. A ~ynthelic analysis ofa rare Arizona species, controlled crossing and backcrossing experi Purshiasubinlegra (Ro>a