Specimen Examined: Utah, Wayne County: Sokoloff et al. 1314 (CAN).

Found growing in silty sediment in Copernicus Valley, this species has been reported from Capitol Reef National Park (as var. argentea) (Fertig 2009), as uncommon in the San Rafael Swell (Harris 1983) and as uncommon in Glen Canyon National Recreation Area (Hill and Ayers 2009). Based on leaf shape, this specimen may be var. rydbergii following Welsh (2003), but as this collection is immature, we have only identified it to species.

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1318 (CAN).

This shrub is widespread throughout Utah's deserts (Welsh 2003) and is common in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009) and present in the Orange Cliffs region (Shultz et al. 1987). The nominate variety, var. canescens, is widespread throughout the species range, following Welsh (2003). In southern Utah and around MDRS, this species is distinguished by its four-winged fruiting bracteoles (Andersen 1996).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1320 (CAN, UTC).

This native annual species is commonly found on wetter, sub-alkaline clay (Holmgren 2003). This species was only recorded from the MDRS area in the immediate vicinity of the Hab, in lower areas where precipitation might accumulate in wet months (Fig. 4b). This species was previously recorded as occasional in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009) and occasional in Glen Canyon National Recreation Area (Hill and Ayers 2009) as Monolepis nuttaliana (Schult.) Greene; however, recent phylogenetic work places this species in Blitum L. (Fuentes-Bazan et al. 2012).

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1271 (CAN); 1319 (CAN).

A common sight in the MDRS area (Fig. 4c), this species can be distinguished from the sympatric (and closely-related) Allium textile A.Nelson & J.F.Macbr. by its 3-5-veined spathe bracts (as opposed to 1-veined in A. textile) (McNeal and Jacobsen 2002). This species has been previously reported from Capitol Reef National Park (Fertig 2009), as uncommon in Glen Canyon National Recreational Area (Hill and Ayers 2009) and uncommon in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1297 (CAN, UTC).

This taxon was only encountered in the sheltered sandy wash south of BLM road 1104, with a unique local vegetation including Populus fremontii subsp. fremontii and Symphoricarpos longiflorus (Fig. 4d, e). Recorded as common in washes and roadsides in the San Rafael Swell (Harris 1983), the protected valley in the wash likely provides a warmer and less windy environment, providing an ideal microhabitat for multiple species not seen elsewhere near MDRS. This taxon has also been recorded from Capitol Reef National Park - as Rhus aromatica var. trilobata (Nutt.) A. Gray - (Fertig 2009) and as common in Glen Canyon National Recreation Area (Hill and Ayers 2009).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1273 (CAN, UTC).

This species was occasionally encountered throughout the MDRS area (Fig. 4f). This variable species has been reported from Capitol Reef National Park (Fertig 2009), as occasionally occurring in Glen Canyon National Recreation Area (Hill and Ayers 2009) (in both locations as Cymopterus acaulis var. fendleri (A. Gray) Goodrich), as present in the Orange Cliffs (Shultz et al. 1987) and common in the San Rafael Swell (Harris 1983) (in both locations as Cymopterus fendleri A. Gray). Current taxonomic concepts place both C. acaulis (including var. fendleri) and C. fendleri in C. glomeratus (Sun et al. 2005).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1289 (CAN, UTC).

This monotypic species was encountered sporadically on sandy soils east of MDRS (Fig. 5a). Endemic to the Colorado Plateau in southeast Utah and northern Arizona (Reveal and Utech 2002), this species has been reported from the San Rafael Swell, where it is common (Harris 1983), as present in Capitol Reef National Park (Fertig 2009) and from Glen Canyon National Recreation Area (Hill and Ayers 2009), where it is uncommon.

a

b

c

d

Figure 5.

Asparagaceae. Photos by P.C. Sokoloff.

a: Eremocrinum albomarginatum, habit (Sokoloff et al. 1289).  
b: Yucca harrimaniae, habitat (Sokoloff et al. 1298).  
c: Yucca harrimaniae, habit (Sokoloff et al. 1298).  
d: Yucca harrimaniae, developing inflorescence ("Hab Ridge" west of MDRS).  

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1298 (CAN).

This species was encountered infrequently, only on the top of "Hab Ridge" and in the sandy wash south of BLM road 1104 (Fig. 5b, c, d). Following Neese and Welsh (1985), these plants would be considered var. harrimaniae; however, recent treatments do not recognise varieties within this species (Hess and Robbins 2002). This species has been reported as common in the San Rafael Swell (Harris 1983), uncommon in Glen Canyon National Recreation Area (Hill and Ayers 2009) and present in Capitol Reef National Park (as var. harrimaniae) (Fertig 2009).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1293 (CAN, UTC).

This species was not yet flowering when collected during our field season, but the characteristically hairy, dissected leaves made identification relatively straightforward (Morefield 2006). Found across the southwest United States (Andersen 1996), it is common in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009), present in the Orange Cliffs area (Shultz et al. 1987) and widespread in Glen Canyon National Recreation Area (Hill and Ayers 2009). This species, along with its congener Chaenactis fremontii Gray, is believed to have arisen from independent aneuploid reduction events in C. gabriuscula DC. (Kyhos 1965).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1277 (CAN, UTC).

While our specimen was not flowering at the time of collection (Fig. 6a), we were able to identify this annual species on the basis of the species' distinctive leaf morphology (David 2006). It is common in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009) and occasional in Glen Canyon National Recreation Area (Hill and Ayers 2009).

a

b

c

d

Figure 6.

Asteraceae. Photos by P.C. Sokoloff.

a: Malacothrix sonchoides, basal rosette (Sokoloff et al. 1277).  
b: Prenanthella exigua, habit (Sokoloff et al. 1306).  
c: Tetradymia glabrata, habit (Sokoloff et al. 1316).  
d: Tetradymia glabrata, leaf detail (Sokoloff et al. 1316).  

Specimens Examined: Utah, Emery County: Sokoloff et al. 1263 (CAN). Wayne County: Sokoloff et al. 1306 (CAN).

These young specimens possess toothed, black-spotted basal leaves which appear to be uncommon in the species (Fig. 6b); neither species accounts in the Flora of North America (Chambers 2006) nor A Utah Flora (Welsh et al. 1993) mention this trait and a search online (SEINet) only found two specimens with similar colouration (Lehto 23527 [ASU 0103025] and Williams 83-56-14 [NESH 81108]). It is reported as common in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009), occasional in the Glen Canyon National Recreation Area (Hill and Ayers 2009) and present in the Orange Cliffs region (Shultz et al. 1987). Previously treated as Lygodesmia exigua A. Gray, Spencer Tomb (1972) re-established the species in Prenanthella (following Rydberg), based on chromosome number and pollen morphology. Molecular work by Lee et al. (2002) found this species to form a clade with Pleiacanthus spinosus (Nutt.) Rydb., another species formerly placed in Lygodesmia.

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1316 (CAN, UTC).

Common in the San Rafael Swell (Harris 1983) and present in Capitol Reef National Park (Fertig 2009), this taxon is readily distinguished from other Tetradymia species in southern Utah by its spreading, club-shaped, glabrous secondary leaves (Fig. 6c, d) (Strother 1974, Strother 2006). This species is known to cause liver toxicity in livestock (Jennings et al. 1978).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1276 (CAN, UTC).

Variety elachantha is the more common infraspecific taxon of this annual species (Johnston 1959) and is the only variety present in Utah (Welsh et al. 1993). This taxon is common in the San Rafael Swell (Harris 1983), widespread in Glen Canyon National Recreation Area (Hill and Ayers 2009), present in Capitol Reef National Park (Fertig 2009) and present in the Orange Cliffs region as Cryptantha crassisepala s.l. (Shultz et al. 1987). This taxon is common throughout the MDRS operational area (Fig. 7a, b).

a

b

c

d

e

f

Figure 7.

Boraginaceae. Photos by P.C. Sokoloff.

a: Cryptantha crassisepala var. elachantha, habit (Sokoloff et al. 1276).  
b: Cryptantha crassisepala var. elachantha, inflorescence (Sokoloff et al. 1276).  
c: Oreocarya flava, habit (Sokoloff et al. 1275).  
d: Oreocarya flava, inflorescence (Sokoloff et al. 1291).  
e: Oreocarya flavoculata, habit (Sokoloff et al. 1268).  
f: Oreocarya flavoculata, inflorescence (Sokoloff et a. 1268).  

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1275 (CAN, UTC); 1291 (CAN, UTC).

Common throughout southeast Utah (Higgins 1971, Payson 1927), this yellow-flowered species is distinctive in the MDRS area (Fig. 7c, d). Previously placed in Cryptantha, recent phylogenetic work has shown that genus to be polyphyletic and resurrected several genera previously submerged into Cryptantha as sections or subgenera (Hasenstab-Lehman and Simpson 2012, Mabry and Simpson 2018).

As Cryptantha flava (A. Nelson) Payson, this species has been reported as common in the San Rafael Swell (Harris 1983) and Glen Canyon National Recreation Area (Hill and Ayers 2009), as present in Capitol Reef National Park (Fertig 2009) and present in the Orange Cliffs region (Shultz et al. 1987).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1268 (CAN, UTC).

Only encountered once in the MDRS area near Salt Wash (Fig. 7e, f), this species is common in the southwest United States (Higgins 1971). This species was also formerly placed in Cryptantha, until recent phylogenetic work confirmed the monophyly of Oreocarya (Hasenstab-Lehman and Simpson 2012, Mabry and Simpson 2018). This species is present in the Orange Cliffs Region (Shultz et al. 1987), occasional in Glen Canyon National Recreation Area (Hill and Ayers 2009), present in Capitol Reef National Park (Fertig 2009) and common in the San Rafael Swell (Harris 1983).

Specimens Examined: Utah, Emery County: Sokoloff et al. 1260 (CAN, UTC). Wayne County: Sokoloff et al. 1309 (CAN, UTC).

This species was encountered occasionally on rocky hilltops and raised clay swells in the MDRS area (Fig. 8a, b, c). Previously treated as Phacelia crenulata var. corrugata (A. Nelson) Brand (Welsh et al. 1993), molecular evidence supports the recognition of this taxon at the species level (Walden et al. 2014, Walden et al. 2016). This species is commmon in the San Rafael Swell (Harris 1983) and common in Glen Canyon National Recreation Area (Hill and Ayers 2009). Phacelia crenulata Torr. ex S. Watson is reported as present in the Orange Cliffs region (Shultz et al. 1987), though their taxonomic concept may have included P. corrugata.

a

b

c

d

e

f

Figure 8.

Boraginaceae. Photos by P.C. Sokoloff.

a: Phacelia crenulata var. corrugata, habitat (Sokoloff et al. 1260).  
b: Phacelia crenulata var. corrugata, habit (Sokoloff et al. 1260).  
c: Phacelia crenulata var. corrugata, inflorescence (Sokoloff et al. 1309).  
d: Phacelia demissa var. demissa, inflorescence (Sokoloff et al. 1308).  
e: Phacelia demissa var. demissa, habit (Sokoloff et al. 1312).  
f: Tiquilia latior, habit (Sokoloff et al. 1290).  

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1308 (CAN); 1312 (CAN, UTC).

Common on the silty flats of Copernicus Valley and on clay formations around the MDRS area (Fig. 8d, e), this species is endemic to the Four Corners States and Wyoming (Soreng et al. 1984). This taxon is present in Capitol Reef National Park (Fertig 2009), common in Glen Canyon National Recreation Area (Hill and Ayers 2009) and occasional in the San Rafael Swell (Harris 1983). Harris (1983) also reported Phacelia demissa var. heterotricha J.T. Howell from the San Rafael Swell; however, that variety is now considered a synonym of var. demissa (Welsh et al. 1993). Phacelia demissa var. minor N.D. Atwood is found outside the MDRS area in the Uintah Basin (Welsh et al. 1993).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1290 (CAN).

Only encountered once in the MDRS area on sandy plains (Fig. 8f), this species is endemic to the south-western United States and is found in Utah, Arizona and Nevada (Higgins 1979, Moore and Jansen 2007). This species is present in Capitol Reef National Park (Fertig 2009), common in Glen Canyon National Recreation Area (Hill and Ayers 2009) and occasional in the San Rafael Swell (Harris 1983).

This invasive weed was photographed (Fig. 9) in the vicinity of the Burpee Dinosaur Quarry north of MDRS, but was not collected at that time. It is common across the western United States (Rollins 1980) where it readily grows in disturbed areas, fields and along roadsides (Al-Shehbaz 2010d). This species has been reported from Capitol Reef National Park (Fertig 2009) and as uncommon in the San Rafael Swell (Harris 1983).

a

b

c

d

e

f

Figure 9.

Brassicaceae. Photos by P.C. Sokoloff.

a: Chorispora tenella, habit (vicinity of Burpee Dinosaur Quarry).  
b: Descurainia pinnata subsp. brachycarpa, inflorescence (Sokoloff et al. 1262).  
c: Descurainia pinnata subsp. brachycarpa, habit (Sokoloff et al. 1262).  
d: Streptanthella longirostris, inflorescence (Sokoloff et al. 1261).  
e: Streptanthella longirostris, habit (Sokoloff et al. 1261).  
f: Strigosella africana, habit (Sokoloff et al. 1278).  

Specimens Examined: Utah, Emery County: Sokoloff et al. 1262 (CAN, UTC). Wayne County: Sokoloff et al. 1303 (CAN).

Widespread throughout much of North America (Goodson and Al-Shehbaz 2010), this species was encountered sporadically on rocky ridges and hilltops (Fig. 9). Descurainia pinnata (not determined to subspecies) is reported as common in Glen Canyon National Recreation Area (Hill and Ayers 2009) and present in the Orange Cliffs Region (Shultz et al. 1987), while this taxon is reported as uncommon in the San Rafael Swell (Harris 1983) and present in Capitol Reef National Park (Fertig 2009) as Descurainia pinnata var. intermedia (Rydberg) C. L. Hitchcock - a synonym of subsp. brachycarpa (Goodson and Al-Shehbaz 2010).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1266 (CAN).

This well-known selenophyte (Feist and Parker 2001) was only encountered once in the MDRS area, near Salt Wash. Delimitation of varieties in this species has changed through time (Rollins 1939, Lichvar 1983, Turner 2004); here we follow Al-Shehbaz (2010a). This taxon is reported as widespread in Glen Canyon National Recreation Area (Hill and Ayers 2009). Stanleya pinnata is reported from the Orange Cliffs region (Shultz et al. 1987) and Capitol Reef National Park (Fertig 2009) and as common in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Emery County: Sokoloff et al. 1261 (CAN).

This specimen is common in the MDRS area (Fig. 9d, e) and across the south-western United States (Al-Shehbaz 2010c). Phylogenetic work that includes this currently monotypic genus has shown that it is not monophyletic and that future taxonomic revision may be required (Ivalú Cacho et al. 2014). This species is present in the Orange Cliffs region (Shultz et al. 1987), widespread in Glen Canyon National Recreation Area (Hill and Ayers 2009), present in Capitol Reef National Park (Fertig 2009) and common in the San Rafael Swell (Harris 1983).

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1269 (CAN, UTC); 1278 (CAN, UTC).

Commonly seen across the MDRS area (Fig. 9f), this invasive weed proliferates in disturbed areas across the western United States (Al-Shehbaz 2010b, Rollins 1980). This species has been reported as common in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009) and as occasional in Glen Canyon Recreation Area (Hill and Ayers 2009). This species was recorded in these inventories as Malcolmia africana (L.) W.T. Aiton; however, it is now placed in Strigosella (Al-Shehbaz et al. 2014, Botschantzev 1972).

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1284 (CAN); 1296 (CAN, UTC).

This species was only encountered twice in the MDRS area (Fig. 10a), including several large plants in a sheltered shady wash with other locally-unique species, such as Populus fremontii var. fremontii and Rhus trilobata var. trilobata. This species is present in the Orange Cliffs region (Shultz et al. 1987), present in Capitol Reef National Park (Fertig 2009), occasional in the Glen Canyon National Recreation Area (Hill and Ayers 2009) and occasional in the San Rafael Swell (Harris 1983).

a

b

Figure 10.

Caprifoliaceae, Cleomaceae. Photos by P.C. Sokoloff.

a: Symphoricarpos longiflorus, habit (Sokoloff et al. 1296).  
b: Cleomella palmeriana, habit (Sokoloff et al. 1311).  

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1311 (CAN, DAO, UTC).

Abundantly common on the silty floor of Copernicus Valley north of MDRS (Fig. 10b), where it was found growing with Phacelia demissa var. demissa, this annual plant is endemic to the Four Corners states (Vanderpool 2010). Infraspecific taxa are no longer recognised in this species following the transfer of C. palmeriana var. goodrichii Welsh to C. hillmanii var. goodrichii (S. L. Welsh) P.K. Holmgren (Holmgren 2004, Roalson et al. 2015), a move supported by genetic sequence data (Riser II et al. 2013). This species is common in Glen Canyon National Research Area (Hill and Ayers 2009), present in Capitol Reef National Park (as C. palmeriana var. palmeriana) (Fertig 2009) and occasional in the San Rafael Swell (Harris 1983).

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1265 (CAN, UTC); 1299 (CAN, UTC).

Occasionally encountered in the MDRS area, this spring-flowering species was conspicuous in sandy washes (Fig. 11c, d). This variety is the only member of this widespread compound species present in Utah, where it is relatively common (Barneby 1964, Welsh et al. 1993, Welsh 2006). This taxon is present in the Orange Cliffs region (Shultz et al. 1987), present in Capitol Reef National Park (Fertig 2009), common in Glen Canyon National Recreation Area (Hill and Ayers 2009) and common in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1286 (CAN, UTC).

Given the non-flowering nature of this specimen, our identification here is tentatively made, based on vegetative morphology. This species was only encountered once in the MDRS area. This species is endemic to this region (Barneby 1964, Welsh et al. 1993, Welsh 2006) and, though not listed at the state or federal level, it is listed as a "Category C3 Non-Candidate" species in the "Watch" category of an inventory of Utah's sensitive plant life (Utah Division of Wildlife Resources 1998). This species is present in Capitol Reef National Park (Fertig 2009), occasional in Glen Canyon National Recreation Area (Hill and Ayers 2009) and occasional in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1301 (CAN, UTC).

Only seen once along the side of a road northeast of MDRS, this large, showy milkvetch is apparently uncommon in the operational area (Fig. 11e). Barneby (1964) and Welsh (2006) largely agree on the infraspecific taxonomy of this species - Welsh describes a fourth variety from northwest Utah in addition to the three varieties present in both treatments. As our specimen was flowering, we have only identified it to species. This species is present in the Orange Cliffs region (Shultz et al. 1987), occasional in Glen Canyon National Recreation Area (Hill and Ayers 2009), present in Capitol Reef National Park (as var. praelongus) (Fertig 2009) and uncommon in the San Rafael Swell (as var. praelongus) (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1280 (CAN, DAO, UTC).

Occasional on sandy soils northeast of MDRS, this species is endemic to the San Rafael Swell and surrounding deserts (Barneby 1964, Welsh et al. 1993, Welsh 2006). As with Astragalus pardalinus, A. woodruffii is not state- or federally-listed, but is listed as category C3 Non-Candidate" species in the "Watch" category in Utah's sensitive plant life survey (Utah Division of Wildlife Resources 1998). This species is present in Capitol Reef National Park (Fertig 2009) and uncommon in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1280 (CAN, MT, UTC).

This species was occasionally encountered on sandy plains northeast of MDRS (Fig. 11f). Endemic to south-eastern Utah and adjacent Colorado (Simpson and Ulibarri 2006), this species is the northernmost member of a predominantly Central and South American genus (Simpson et al. 2004). This species is common in the San Rafael Swell (Harris 1983) and there are unconfirmed reports for Capitol Reef National Park (Fertig 2009).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1287 (CAN, UTC).

This species was occasionally encountered on sandy plains northeast of MDRS (Fig. 12a). Welsh et al. (1993) describes three varieties present in Utah, but notes that, in his opinion, there was insufficient evidence to recognise them within the state. As our specimen is vegetative, we were unable to ascribe it to any variety. This species is present in the Orange Cliffs (Shultz et al. 1987), common in the San Rafael Swell (as L. pusillus var. pusillus and L. pusillus var. rubens (Rydb.) Welsh) (Harris 1983), present in Capitol Reef National Park (as L. pusillus var. pusillus and L. pusillus var. intermountanus (Heller) C.P. Sm.) (Fertig 2009) and present in Glen Canyon National Recreation Area (as L. pusillus subsp. pusillus and L. pusillus subsp. rubens (Rydb.) D.B. Dunn) (Hill and Ayers 2009).

a

b

c

d

e

f

Figure 12.

Fabaceae, Nyctaginaceae, Onagraceae, Poaceae, Polygonaceae. Photos by P.C. Sokoloff.

a: Lupinus pusillus, habit (Sokoloff et al. 1287).  
b: Abronia elliptica, habit (Sokoloff et al. 1292).  
c: Camissonia eastwoodiae, habit (Sokoloff et al. 1307).  
d: Eremopyrum triticeum, habit (Sokoloff et al. 1321).  
e: Eremopyrum triticeum, inflorescences (Sokoloff et al. 1321).  
f: Eriogonum wetherillii, habit (Sokoloff et al. 1272).  

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1315 (CAN, UTC).

Only encountered once as a vegetative specimen on "Hab Ridge", on gravelly clay soil characteristic of its range in Utah (Schenk and Hufford 2016), this species may be more commonly encountered during flowering, when the plants are more conspicuous. This species is reported as occasional in Glen Canyon National Recreation Area (Hill and Ayers 2009), uncommon in the San Rafael Swell (Harris 1983) and present in Capitol Reef National Park (Fertig 2009).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1292 (CAN, UTC).

The taxonomy of A. fragrans and A. elliptica A. Nelson has a complicated history in Utah, with Welsh et al. (1993) lumping both species in the state together, despite earlier (Galloway 1975) and later (Galloway 2003) treatments separating them based on fruiting characters. Here we follow Galloway (2003); however, the specimens we collected were vegetative (Fig. 12b). Pending collection of material with mature fruits, we tentatively assign this specimen to A. elliptica, as continuing work by Eric LoPresti indicates that the majority of specimens from this complex in cental Utah properly belong in this species, particularly around the San Rafael Swell (Mike Moore, personal communication, 2020). Abronia elliptica is reported as common in the San Rafael Swell (Harris 1983) and present in the Orange Cliffs Region (Shultz et al. 1987), while A. fragrans is not recorded at all. Conversely, A. fragrans (with A. elliptica in synonymy) is reported as present in Capitol Reef National Park (Fertig 2009) and widespread in Glen Canyon National Recreation Area (Hill and Ayers 2009). Further work will be needed to verify the true range of this species in the regions surrounding MDRS.

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1307 (CAN); 1313 (CAN, UTC).

A Colorado Plateau endemic (Welsh et al. 1993), this species was encountered occasionally around MDRS on the clay sediments in Copernicus Valley and on grey Mancos Shale layers (Fig. 12c), consistent with published habitat descriptions for this species (Raven 1969). Reported as common in the San Rafael Swell (Harris 1983), present in Capitol Reef National Park (Fertig 2009) and common in Glen Canyon National Recreation Area (Hill and Ayers 2009).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1288 (CAN).

This species was only encountered once in the MDRS area as an inconspicuous vegetative specimen; fieldwork during this species' flowering time may reveal it to be common in the area. The taxonomy of this group has fluctuated, with Welsh et al. (1993) recognising two varieties in Utah and Evans et al. (2005) recognising five subspecies across this species range. As the specimen cited here is immature, we have only determined it to the species level. This species has been reported from the Orange Cliffs (Shultz et al. 1987), as widespread in the Glen Canyon National Recreation Area (Hill and Ayers 2009), present in Capitol Reef National Park (Fertig 2009) and as common in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1321 (CAN, UTC).

Though not reported from the San Rafael Swell (Harris 1983), Capitol Reef National Park (Fertig 2009) or Glen Canyon National Recreation Area (Hill and Ayers 2009), Frederiksen (2007) reports this annual weed as occurring across western North America, scattered across disturbed sites and Barkworth et al. (1983) reports this species as occurring across the Intermountain Region. At MDRS, this species was only found in areas immediately adjacent to the station (Fig. 12d, e), in disturbed, saline clay sediment matching the habitat description in Banner et al. (2011).

Specimens Examined: Utah, Wayne County: Sokoloff et al. 1274 (CAN, UTC); 1295 (CAN, UTC).

Widespread across North America (Lonard 2007), this annual taxon was commonly encountered across the MDRS area during our study (Fig. 13). This genus is sometimes placed in Festuca (Lonard and Gould 1974). As Festuca octoflora Walter, this species is reported from Capitol Reef National Park (Fertig 2009). As Vulpia octoflora, this species is reported as widespread in Glen Canyon National Recreation Area (Hill and Ayers 2009), present in the Orange Cliffs region (Shultz et al. 1987) and occasional in the San Rafael Swell (Harris 1983).

Figure 13.  

Vulpia octoflora var. octoflora, habit (Sokoloff et al. 1274). Photo by P.C. Sokoloff.

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1305 (CAN, UTC).

Common in the Four Corners states, Wyoming, South Dakota and Nebraska (Reveal 2005), this species was only encountered once in the MDRS area. This species is present in Capitol Reef National Park (Fertig 2009) and uncommon in the San Rafael Swell (Harris 1983).

Specimens Examined: Utah, Wayen County: Sokoloff et al. 1270 (CAN); 1272 (CAN, UTC).

Encountered occasionally in the MDRS area on sandy washes and clay soils (Fig. 12f), this species is endemic to the Four Corners states and common in southeast Utah (Reveal 2005). This species is present in the Orange Cliffs Region (Shultz et al. 1987), common in Glen Canyon National Recreation Area (Hill and Ayers 2009), present in Capitol Reef National Park (Fertig 2009) and occasional in the San Rafael Swell (Harris 1983).

Specimen Examined: Utah, Wayne County: Sokoloff et al. 1300 (CAN, UTC).

This species is common along the banks of the Fremont River south of the MDRS area, just south of Utah State Route 24 (P. Sokoloff, pers. obs.). This particular collection is the nearest-known population to MDRS and the only one encountered in the operational area in many years of fieldwork (S. Rupert, pers. obs). Consisting of one large tree and two smaller saplings (Fig. 14), this population was found in a protected sandy wash with other unique species in the MDRS area, including Rhus trilobata var. trilobata and Symphoriocarpos longiflorus. This taxon, recorded as Populus fremontii, has been reported as common in the San Rafael Swell (Harris 1983), occasional in the Glen Canyon National Recreation Area (Hill and Ayers 2009) and present in the Orange Cliffs region (Shultz et al. 1987). This taxon has also been reported as present in Capitol Reef National Park as Populus fremontii var. fremontii (Fertig 2009). Following Eckenwalder (2010), these plants are all part of the more widely distributed nominate subspecies; the other subspecies: P. fremontii subsp. mesetae Eckenwalder, is only found in Texas.

Figure 14.  

Populus fremontii subsp. fremontii, habit and habitat (Sokoloff et al. 1300). Photo by P.C. Sokoloff.