Table Of ContentMadrono, Vol. 53, No. 3, pp. 278-281, 2006
A NEW CLUB CHOLLA, GRUSONIA ROBERTS11 (CACTACEAE)
FROM BAJA CALIFORNIA SUR, MEXICO
Jon p. Rebman
San Diego Natural History Museum, P.O. Box 121390, San Diego, CA 92112-1390
[email protected]
Abstract
A new species ofclub cholla (Grusonia robertsii) endemicto the Vizcaino Desert ofBaja California
Sur is described here for the first time. Distribution, associated vegetation, rarity, affinities to other
related species, a botanical illustration, a key to the species in the genus Grusonia of the Lower
California region, and a key for the generic reclassification of Opimtia sensu lato as recognized by
Wiggins (1980) but currently treated as three different genera in the region are also presented.
Resumen
Se describe aqui por primera vez una especie nueva de casa rata {Grusonia robertsii) endemica del
Desierto Vizcaino, del estado de Baja California Sur. Se presentan la distribucion, vegetacion
asociada, rareza, afinidad con otras especies en el genero, una ilustracion del nuevo taxon, una clave
a las especies en el genero Grusonia de la peninsula de Baja California, y una clave para la
reclasificacion genericade Opuntiasensu latodeWiggins(1980), queactualmenteestratadacomotres
generos diferentes en esta region, y que tambien se presentan aqui.
Key Words: Cactaceae, Grusonia, Corynopuntia, Baja California Sur, Mexico.
Lower California is comprised oftwo Mexican Grusonia robertsii Rebman, sp. nov. (Fig. 1)
tsthaattesar(eBapjoaliCtiacHaflolyrndiiaviadnedd BatajtaheCa2l8itfhornpiaraalSluerl). Type. MEXICO, Baja California Sur: Vizcaino '
Desert near 27=19'N, 113°08'W, between San
TGsuhulelasfeaonfsdtCaatiletsisfacodrojnmaipcarei(nsSteeaitsholefanCBdosarjtlaeoscC)aatHaefndodrinntihbeaoPtpaehcniitfnhi-ec AIRgeSnbUam,ciaoBnCa7Mn7dE9X5G,u(ehrHorCleIortBoy)p.eN:egrSoD, 21848O2c87t;obeisrot2y0p0e1s,: ||
Ocean. This region supports a wealth of plant i
species diversity. Wiggins (1980) estimated that Paratypes. MEXICO, Baja California Sur:
2958 total taxa including 686 endemic taxa occur Vizcaino Desert, between San Ignacio and
in Lower CaHfornia or an endemism rate of Guerrero Negro, 10 May 1992, Rebman 1361
23.2%, but recent plant discoveries and a more (ASU 187542, SD 155542); 10 March 1998,
complete overview of the literature suggests that Rebman 4836 & N. Roberts (SD 143343).
the flora consists of more than 4000 plant taxa
with a rate ofendemism closer to 30% (Rebman Note. The specific locations ofthis new cactus
2001). The Cactaceae are a conspicuous and species including detailed latitude and longitude
diverse component in most areas and plant coordinates have been intentionally omitted due !
communities of Lower CaHfornia. According to to the lack ofknown populations, its rarity in the
Rebman (2001), the Cactaceae of Lower CaHfor- field, and the popularity that cacti have in the
;
nia are represented by 15 genera, 104 species, and hobby/horticultural industry. if
129 total taxa. Of these, 71 species and 92 taxa Latin diagnosis. Grusonia kunzei (Rose) Pin-
areendemic to the region, a 68.3% endemism rate kava simile, sed differt fructibus brevioribus 20- |i
for species and 71.3% for taxa. The genus 35 mm longis, areoHs per fructum paucioribus \
BOrpiutnttoina&MiRlloesre s[eCnosruynolaptuonti(iancFl.udMi.ngKGnruutshonitao (25 30), et spinis majoris caulinis complanatis I^j
leviter basi.
some authors], Cylindropuntia (Engelm.) F. M. J!i
Knuth, and Opuntia sensu stricto) was considered English diagnosis. This species resembles Gru-
to have the highest number ofoverall taxa (41) in sonia kunzei but differs in having a shorter fruit, ;
mm 1;
the region before it was split into three genera 20-35 in length, fewer areoles (25-30) per
(Anderson 2001). Only two species in the genus fruit, and major spines ofthe stems only slightly i
Grusonia (G. invicta (Brandegee) E. F. Anderson flattened at the base.
and G. kunzei (Rose) Pinkava) were previously Shrubs, low to nearly mat-forming, to 45 cm
known to occur on the peninsula of Baja tall. Stem segments succulent, 7.5-11 X 2.5-
CaHfornia. 3.5 cm (Fig. lA); tubercles prominent, 20-35 X
;
2006] REBMAN: NEW CLUB CHOLLA FROM BAJA CALIFORNIA SUR 279
5-13 mm. Areoles 6-7 x 4 6 mm with cream to Fruits sub-spheric to short turbinate, 20-35 X 15-
mm
gray wool. Spines 12-20 per areole (Fig. IB), 22 with 25 30 areoles; covered with long,
lavender-gray (yellowish on one individual), deciduous glochids when young but at maturity,
uniformly distributed along the stem, the central, mostly spineless with up to 7 spines strongly
major ones divergent, slightly flattened to attached in some scattered areoles; yellow and
strongly angled at base, 0^ sheathless, bristle- fleshy when ripe. Seeds 25-35 perfruit, 3^.5 mm
like spines. Glochids in a sparse, apical crescent in diameter (Fig. IC).
on stem areoles, gray to dark brown, 2-9 mm;
fruit and flower areoles with an apical crescent of Distribution and Habitat. Endemic to Baja
cream to light yellow glochids, 2-6 mm; plus in California Sur; individuals of Grusonia robertsii
flower areoles other glochids are present, orange- occur on flat plains and lower slopes ofvolcanic
brown to gray, up to 25 mm long. Flowers mountains in coarse sandy substrates scattered
yellow; filaments green; styles greenish-yellow. with large basaltic rocks; elevation 120-240 m;
MADRONO
280 [Vol. 53
Vizcaino Desert associated with a succulent a low-growing habit; all are characteristics ofthe
desert scrub dominated by Yucca valida Brande- genus Grusonia. However, the shape ofthe fertile
gee, Pachycereus pringlei (S. Watson) Britton & fruits is not like other known species in the genus,
Rose, Fouquieria diguetii (Tiegh.) I. M. Johnst., which is usually narrowly obconic to ellipsoid. In
Bursera microphylla A. Gray, Stenocereus gum- fact, the fruit of this new species is more similar
mosus (Engelm.) Gibson & Horak, Grusonia to that found in various species of the genus
invicta, Cylindropuntia choUa (F. A. C. Weber) Cylindropuntia which are short-turbinate to sub-
F. M. Knuth, and Echinocereus brandegeei spheric. It should be noted that there are no
(Coulter) K. Schum. Additional associates in- known hybrids between the opuntioid genera
clude: Atrip/ex barclayana (Benth.) D. Dietr., Cylindropuntia and Grusonia, and that the high
Cylindropuntia alcahes (F. A. C. Weber) F. M. seed set inthefruits ofthisnewtaxonwould seem
Knuth, Euphorbia misera Benth., Ferocactus to indicate that it is reproducing by seeds.
&
peninsulae Britton Rose, Frankenia palmeri S. Part of the reason for its paucity of field
Watson, Lophocereus schottii (Engelm.) Britton observations and collections is due to the
& Rose var. schottii, Mammillaria dioica K. difficulty in differentiating this new species from
Brandegee, M. lewisiana Gates, Pedilanthus other sympatric cacti at a distance. It is
macrocarpus Benth., Stenocereus thurberi (En- convergent in growth habit to Grusonia invicta
gelm.) Buxbaum, and Tillandsia recurvata L. and to Echinocereusbrandegeei, both ofwhichare
comm.on species in the vegetation of the type
Phenology. Flowers in May; fruits persist on locality. All three species are low-growing to mat-
plant until at least November. forming shrubs that are densely shrouded with
Etymology. This new cactus is being named in gray spines and without close inspection, the
honor of Dr. Norman Roberts, a friend, natu- vegetative parts of these species are readily
ralist, and explorer of the deserts in Lower confused. Although E. brandegeei has bright
CaUfornia. Dr. Roberts has contributed im- yellow, acicular spines in much ofits distribution,
mensely to our knowledge and enjoyment of it has gray, flattened spines in the region of the
plants in Lower California by publishing a book peninsula near San Ignacio. In truth, I have
entitled "Baja California Plant Field Guide" visited the type locality for G. robertsiiat least six
(Roberts 1989), and by promoting and facilitat- different times and almost each visit has revealed
ing botanical studies and explorations in the a new individual in the population (the last time
region. with five separate individuals observed was in
October 2001). Because the vegetation and
habitat in which this new species occurs is quite
Discussion
widespread in this part of the peninsula, it is
Grusonia robertsii, found in the Vizcaino cproombmabolne tthhaant isthcisurrneentwlycklunbownch.olAlsa aismamtotreer
bsDyuemtspeardtitsrtioicfnacnltolryntehwweirtcnhluBGba.jcahionCvlaillcait.fa,oArlnittiahaoSpuupgre,hariisstagtroraorwbese, yo2e0f0l5lfa,ocwt-,Ispdiounbresidenrgvfeoadrmt)rainpooftthotehritsheinnredeiwgviisodpnueacliinespJlaaannlutmaors(yta
most closely related to G. kunzei, which is found 30 km southeast ofthe type locality. Conversely,
minatseoluyth4w5e0stkemrntAoritzhoenan,ortShonionrathaendSanappFreolxiip-e tEhcehrienoacreereoutshleirndcsaacytiiJ.oMneythreanpetnhiantsaullsao oscuccuhraisn
Desert of Baja California.
a widespread habitat and vegetation type of the
In 1992, when I discovered the first individual Vizcaino Desert that are very rare indeed, which
of Grusonia robertsii, I originally thought it to be might also be the case for this new species.
a naturally occurring, intergeneric hybrid be-
tcawheeesn. IGnrtuesrosnpeicaifiicnvihcytbariadnizdatCioynlinidsroapucnotimamoaln- Keytothe SpLeociweesrinCtalhiefGoernniuas Grusonia in
occurrence in the Cactaceae, especially in the
genus Cylindropuntia, and has played an integral 1. Stems subspherical, length < 2 times width;
part in the evolutionary process of the family flowers with reddish filaments
(Pinkava et al. 1998). However, after closer G. invicta (Brandegee) E. F. Anderson.
morphological evaluation and after the discovery 1'. Stems cylindric-clavate, length > 2 times
ofother individuals in the population at the type width; flowers with yellow to green filaments.
alocanleiwt,y ovrearrethsepyeecairess, IinhavtheedegteenrumsineGdruitsotnoiab.e 2. dFrriuci,t4v0e-r7y5smpimny,innlaernrgotwh,lywietlhlip4s0o-i7d0toarecoylleisn,-
Although only six individuals ofthis new species majorspinesofstemareolesstroQglyflattened;
occurs in Arizona, Sonora and northern Baja
have yet been recorded, it does not seem to be of California G. kunzei (Rose) Pinkava.
hybrid origin. This new taxon has spine sheaths 2'. Fruit naked to sparsely spiny, short turbinate
deciduous only at the spine apex, major spines to subspheric, 20-35 mmin length, with 25-30
that are flattened to angled at the base, areoles of areoles; major spines of stem areoles mostly
flowers and fruits with longer tufts of wool, and angled to slightly flattened at base; known
2006] REBMAN: NEW CLUB CHOLLA FROM BAJA CALIFORNIA SUR 281
only from northern Baja California Sur .... Acknowledgments
G. rohertsii J. Rebman. This work was supported in part by funds from the
Cactus and Succulent Society ofAmerica, the National
Separation of the Genus Opuntia Sensu Lato Geographic Society, and the William J. Fulbright/
Garcia-Robles Foundations. My gratitude is extended
The large genus Opuntia sensu lato is currently to Dr. Jose Delgadillo, curator of the BCMEX
being recognized (Anderson 2001) as various Herbarium at the Universidad Autonoma de Baja
smaller, segregate genera. In Lower California, California in Ensenada, Mexico, and to SD Herbarium
the genus Opuntia s.l. as recognized by Wiggins staff and volunteers for the collaborative efforts that
(1980) is now treated as three different genera: facilitate my cactus research. Special thanks to Jennifer
Grusonia (or Corynopuntia for some authors), Zee for the illustration, Denise Brook-Schwartz for
Cylindropuntia, and Opuntia s.s. These three graphics assistance, Isolina Martinez for Spanish trans-
genera can easily be distinguished based upon lation. Dr. Donald Pinkava for his continued guidance
and consultation, and to Drs. Mike Simpson, John
vegetative morphology such as stem shape and Mood, and Stephanie Mood foreditingthe manuscript.
spine characters. I am always indebted to the many people who have
joined and helped me with field work on the Cactaceae
Key to the Genera of Lower California ofLower California. A special thanks to the appropri-
Previously Recognized as Opuntia ate Mexican authorities forgrantingpermits and to Dr.
Sensu Lato Exequiel Ezcurra and Patricia Beller for their efforts in
obtaining the papers and permits needed to conduct
1. Stem segments cylindric to clavate; spines field research and collection of plant species in the
variously sheathed (at least when young). region.
2. Stem segments cylindric; trees or shrubs,
erecttodecumbentortrailingbutnotmat- Literature Cited
forming; spine sheaths covering entire
spine and sometimes long-persisting; Anderson, E. F. 2001. The cactus family. Timber
spines round in cross-section Press, Inc., Portland, OR.
Cylindropuntia (chollas). Pinkava, D. J., J. Rebman, and M. Baker. 1998.
2'. Stem segments clavate to spheric; shrubs, Chromosome n—umbers in some cacti of western
low, mat-forming or caespitose; spine North America VII. Haseltonia 6:32^1.
sheaths only covering spine tips and Rebman, J. 2001. Succulent diversity in Lower
usually quickly deciduous; most major California, Mexico. Cactus and Succulent Journal
spines flattened in cross-section (US) 73:131-138.
Grusonia (club chollas). Roberts, N. C. 1989. Baja California plant field guide.
1'. Stem segments flattened into cladodes or Natural History Publishing Co., La Jolla, CA.
rarely subcylindric; spines sheathless Wiggins, L 1980. Flora of Baja California. Stanford
Opuntia (prickly-pears, nopales). University Press, Stanford, CA.
