Schaffnerella Rediscovered ! ( Gramineae , Chloridoideae )

From 1876 to 1880 in San Luis Potosi, Mexico, J. G. Schaffner made the first collections of a small grass that later was named Schaffnerella gracilis (Chloridoideae). The monotypic genus apparently was not encountered again by botanists until 2001, when, during a targeted search, we discovered it in the Sierra de San Miguelito growing along the Rio Potosino, ca. 6 air km southwest of the city of San Luis Potosi. Most of the 100-150 plants encountered along a 3-km stretch of the Rio Potosino above the village of Escalerillas and reservoir El Potosino were growing in a moist alluvium of rock and sand. Historically known to occur some 10 km or more downstream near Morales, a village at the western edge of the city of San Luis Potosi, S. gracilis has been impacted adversely by the creation of dams. Much additional field work is required to determine the geographic range and frequency of the species. Also needed are life history and population-level studies.

In 1882 George Bentham described the genus Schaifnera and species S. gracilis from plants collected by J. G. Schaffner in the state of San Luis POtOSI, Mexico.Schaffnera turned out to be a later homonym and was renamed Schaffnerella by Nash (1912).The affinities of this puzzling grass, beyond being a member of subfamily Chloridoideae (e.g., Clayton and Renvoize (986), remained unknown until recently (Columbus et al. 2000, unpubl. data).Adding to its mystery.no specimens known to us had been collected since Schaffner's, over 120 years ago!Was the species now extinct, grazed out by livestock or its former habitat built over?Or was this annual (as suggested by Schaffner's specimens) species still extant , but had been overlooked due to its relatively small stature (stems mostly < 15 Col long, often ascending or decumbent), restricted distribution, and/or limited numbers or absence during drought years?Its distinctive morphology even suggested to us that it may be a transient intergeneric hybrid that Schaffner had happened upon .
Our attempt to relocate S. gracilis in the field began with a study of Schaffner's specimens .Assembling 14 sheets from II herbaria in the United States of America, including POM and RSA, we found that his specimens of the species are not particularly rare.(For a brief biography of Schaffner and a discussion of his San Luis POtOSI collections, see Rzedowski [1959].)Although most specimens are numbered with both 134 and 1070, it became apparent to us that plants were collected at different times, with dates ranging from 1876 to 1880 (two specimens further indicate August), and possibly from different sites.However, only one specimen possesses a specific collection locality and none indicates habitat (besides "mountains") or elevation .One of the specimens has no locality data beyond "Mexico" and half indicate only " Sa n Luis Potosi, Mexico".Another adds "Mountains" and three more, "San Miguelito Gebirge [German , Schaffner's native tongue, for mountain range]" .Wrapping around the west and south sides of the city of San Luis POtOSI, the NNW-SSE trending Sierra de San MigueJito is ca.50 km long and averages ca.20 km wide, and rises from 1900 m on its east side to a maximum elevation of 2870 m.Labels on the two remaining specimens are printed with "ex convalli San Luis Potosf" .As discussed by Rzedowski (1959), it is uncertain how Schaffner delimited the Valley of San Luis Potosi.One of these specimens also bears, in script, "In montibus San Miguelito", and the second, "In montibus Morales" (Fig. I).This latter specimen is by far the most specific as to collection locality.Morales, absent from many maps, is a small village lying at the western edge of the city of San Luis Potosf.It is situated at the mouth of a large canyon, carved out by the Rfo Santiago, leading west into the Sierra de San Miguelito.Although we had determined that Schaffner collected the species on multiple occasions over five years, and that one of his localities was fairly specific, the absence of any reports of Schaffnerella for over a century did not leave us optimistic about finding plants in the wild .
Armed with the foregoing information, in August 200 I we contacted Dr. Jerzy Rzedowski (Institute de Ecologfa, Patzcuaro, Michoacan, Mexico), who founded the herbarium at the Universidad Aut6noma de San Luis Potosi (SLPM) in 1954 and remained there until 1959, and is the authority on Schaffner.He responded with no specific information regarding Schaffnerella, except that he had looked for it on his collecting trips, but indicated that he thought Schaffner had collected a lot in the Sierra de San Miguelito along a road from Escalerillas (along Hwy.80, which crosses the Sierra, ca. 5 air km southwest of the city of San Luis Potosi) to Jesus Marfa (ca .25 air km south of the city), especially around a place named Cueva del Mezquite.Dr. Rzedowski kindly drew and provided a map for us .On none of our purchased maps did we find Cueva del Mezquite or indication of a road leading all the way from Escaleri lias to Jesus Marfa.
On 24 September 200 I we set out from Claremont, California, on a 23-day plant collecting trip that took us to Oaxaca, Mexico.Two days were set aside to search for Schaffnerella.On the evening of 30 Sep we arrived in the city of San Luis Potosf and awoke early the next morning to find the local flora prospering from an abundance of rainfall-important when one is in pursuit of a presumed annual.Rather than begin our search in the area around Morales, a name on a Schaffner specimen but a place now greatly impacted by humans and livestock, we opted to spend the first day searching along the route suggested by Dr. Rzedowski.A several-minute drive on Hwy.80, including a stretch along the picturesque Canon Santiago, took us into the Sierra de San Miguelito and to the village of Escalerillas.Here we asked a local about Cueva del Mezquite and the road to it.To our dismay, although he knew of the place, he said that no road led to it.Rather than hike in, we decided to drive around the west and south flanks of the Sierra to Jesus Marfa, periodically stopping for brief searches in diverse habitats, and try our luck from the other side.That afternoon found us in the small town of Jesus Marfa with some good collections in hand but no Schaffnerella.We inquired about Cueva del Mezquite of a middle-aged man, a mason by profession, whom we encountered.He too knew of this place and indicated that no road went there.However, he did know of a road that went part way, an option we chose.Accompanied by this man (for twice his daily 101 0 0 5 ' W  wage) we cauti ou sly crept northwest in our four-wheeldriv e truc k up tow ard s a large canyon (La Laja) in the Sierra.Th e o ld track was scarcely discernable and had been wa shed out in a number of place s-places our guide fortunatel y knew ho w to ge t aro und.At the mouth o f the ca nyo n, unable to pro ceed farth er by vehicle , we parked and o ur gu ide led us by foot up the canyon for ca . 2 krn until we reached wh at he knew as Cueva, nothing more than a rock overhan g in the ca nyon bottom.Se arching both sides of the can yon for a couple of hours, we saw no sign of Schaffnerel la, a lthough so me pre-anthesis plants of an annual Muhlenbergia Schreb.spec ies drew our attention.With du sk fast approaching, we retreated to the vehicl e and back to the c ity----day o ne had ended.
Our plan for the sec o nd and final day (2 Oc t) of sea rc hing was to s pe nd the first part o f the day looki ng a ro und Mor al es and then hike as far as tim e a llowed from Esca lcri llas to ward s C ue va (Fig. 2) .A few hours o f walking the o pen.rock y rid ge between Mor ale s and Presa San Jose , made interesting by the adjace nt, acti ve rifie target ran ge , yie lded no sign o f o ur mysterio us g ras s.At midmorning we turn ed into the narro w main stree t o f Escalerillas and man aged to locat e a place w ide e no ug h to park the vehicle, then readied o ur packs a nd se t out by foot, under o verca st skies, up the R fo Potosi no, a major tributary o f the RIo Santiago.We found a dirt road that follo wed the ca nyo n a nd soo n we e nco unte red Pre sa El Potosi no , a reservo ir o verloo king Escalerillas .Alon g the way we searc hed the o pe n, rocky s lo pes , be ing teased o nce aga in by a pre-anthesis a nnua l Muhlen b erg ia s pec ies .After ca . 2 km of wa lking we reached the upper end of Pre sa EI Potosino a nd a fter a no ther km the roa d forked, one road rem aining in the bottom , w here a strea m flowed, and the other a ng ling up the northeast side of the canyon.Ab ov e us we o bser ved sizable excavations, accessible fro m the upper road.(Later we learned that the rhyolitic parent material is mined by hand and transported as block s via dump trucks the sho rt distance to E scal erillas, wh ere they are sculpted a nd lathed into statues, founta ins, a nd other decorative objects, and so ld alon g Hw y. 80 which connects the cities of San Lui s Potosf and G uada laj ara, Jalisco.)In orde r to cover as mu ch ground as possible and explore different habitats , we e lec ted to s plit up into tw o gro ups, each foll owing o ne of the roa ds .The g ro up in the ca nyo n bott om searc hed the lo wer s lo pes, bounc- ing from one side of the canyon to the other.Old rock corrals were encountered along the way.Soon the canyon narrowed appreciably, its sides too steep to easily climb, and the group was relegated to proceeding in the rocky, sandy bottom along the stream and road .
After walking a short distance in the canyon bottom , panning intently from side to side at the ground, occasionally glancing ahead at the beckoning high peaks of the Sierra, the lead author's focus was drawn to a small grass growing at the moist edge of the road track.It was instantly recognized as the elusive Scha.ffnerella gracilis.in full flower (Fig. 3-5)!Following a brief yet euphoric celebration, another plant was spotted nearby.Working both up-and downstream, our two groups united for an intensive search of the stream bed.Gradually more plants were discovered , indeed for at least a kilometer farther upstream and all the way back down the stream course to the reservoir.Although we now had a fix on the habitat of Schaffner's grass, finding plants proved to be a challenge because they were sporadic, though sometimes in clusters of several plants, and difficult to see against the rocky background.A few plants were found on a relatively dry, sandy bank, but the remainder of the 100-J 50 plants ultimately discovered were growing on moist alluvium of rock and sand .Based on these field observations and the growth of Due to time constraints, we were unable to expand our search be yond thi s sec tio n of the Rio Potosi no.Sch affnerella gracilis almost certa inly occurs farther up the long can yon , and , from Schaffner's Morales spec ime n, we know that historically it was found some 10 or more km downstream (Fig. 2).A careful search of Rio Santiago between Escaleri lIas and Morales might yield some plants, but thi s area, which includes the 2-4 km-Iong reservoir San Jo se, has been significantly impacted by hum an s.Expl oration of other canyons nearby, especially the lar ge drainage just southwe st of Canon Potosi no, abov e ano ther reservoi r, Gonzalo N. Santos, likel y would bear fruit.
It is clear that creation of dam s has ad versel y impacted Schaffnerella, certainl y by s ubmerg ing habitat , but perhaps also throu gh a reducti on in flood frequency and ma gnitude down stream .Livestock grazing and road s are additional thr eats to the spec ies, as we obse rved .Some of the plants we encountered had been g razed by livestock, and the road in Canon Potosino is located in the bottom in places, including where the first plant was discovered at the edge o f the road track.In o rder to ascertain fully the rarity o f S. g rac ilis and the threats posed to the species, mu ch add itio na l field work is required to establi sh its geogra phic limits and frequen cy, and al so needed are life history and populati on -level stud ies .We hope that o ur redi sc o very will s tim ulate interest in the biology and co nse rv atio n of thi s e lusive , lon g-lost rnon oryp ic genus .

ACKNOWL EDGM ENTS
We are profoundly grateful to Dr. Jerzy Rzedowski for the information he shared, and to Dr. Victor W. St einmann for facilitating communicati on.It is highly prob abl e that we would not have e nco untered the spec ies without Dr.Rzedowski's guid an ce .T he follo win g herbaria provided loans of s pec ime ns : CAS , F, GH , ISC , MICH , MO, UC, US , YU .Dr. Mari a Elena Siqueiro s D. furni shed us with top ographic maps and so ug ht permission on our beh alf to reprodu ce the topo g raphic map in Fig. 2. Plants were co llec ted under OFICIO NUM/SGPNDGVS/4291 from the Direccion General de Vida Silvestre, Secretarfa de Gesti6n para la Proreccion Ambiental, Secreran a de Medi o Ambiente y Recursos Naturales.Dr. Jonath an A. Nourse determined that a rock sample (actually a sc ulpted bu st o f Pan ch o Vill a's cousin) from a quarry in C anon Potosino is rhy olitic.Drs.Rzedowski and John R. Reed er provided helpful reviews of the manu script.

Fig. I .
Fig. I.The most specific of J. G .Schaffner's collections of Schaffnerella gracilis as to locality (GH) , The plant is 12 ern tall.

Fig. 2 .
Fig. 2. Ma p of the red iscovery site .Deno ted by an arrow is the locat ion where Schaffnerella g rac ilis was first e ncou ntered .The topo graphic map is a portion of map F I4A83 (Tepe tate : 1:50,000) from the Institut e Nac ional de Estadistica, Geografia e Info rmat ica (Mexico) .

Fig. 3 .
Fig. 3. Th e redisco very site of Schaffnerella gracilis along the R Io Potosino in the Si erra de San Miguelit o, Sa n Luis Potosi.Mexico.View looking so utheast and ups trea m towards the high reaches o f the S ierr a.