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Past taxonomic confusion in Comarostaphylis is attributable to several reasons, including the similarity in various
reproductive structures between the various species. Floral morphology
is very similar in all taxa of Comarostaphylis, and differences
in the fruit are, with few exceptions, unimportant taxonomically.
The vegetative
organs, however, particularly the leaves, show a great deal of both
intraspecific and interspecific differentiation. Another, and probably
the most important, reason for confusion in Comarostaphylis taxonomy
has been the paucity of adequate herbarium specimens and the absence of
salient field data. Characters such as growth form, flower color,
and habitat are all important to an understanding of the group, but have
rarely been noted by collectors. For these reasons field data and
population samples were critical to understanding the species. Only
when natural populations, with their complete spectrum of variability,
were seen did some relationships become clear. Only rarely does a
taxon in Comarostaphylis have a character state unique to it; in
most cases, particular associations of non-unique character states delimit
taxa. Examples of parallel evolution are common. Further, the
stability of characters can vary widely between taxa, so that a character
important in the delimitation of one taxon may be so unstable as to be
useless for another. Despite these problems of instability and the
paucity of absolute characters, the associations or sets of correlated
characters are constant enough to allow a high degree of predictability
(Diggs, 1995b).
Preliminary pollination studies on Comarostaphylis
glaucescens and C. discolor subsp. manantlanensis indicate
that Apidae, particularly bumblebees, are among the primary pollinators
(Diggs, 1995b). In addition, Diggs has observed bumblebees visiting C. arbutoides and C. mucronata. In addition to bumblebees,
repeated visitation by at least three species of hummingbirds --Amazilia
tzacatl, Hylocharis leucotis, and Cynanthus latirostris--
has been observed on the red-flowered C. glaucescens in Jalisco
(Diggs, 1995b). The small, juicy fruit, sometimes somewhat sweet
in taste, and the color display (red immature fruit are commonly mixed
with dark purple or black mature fruit in most species and form a striking
contrast) suggest animal, possibly bird, dispersal (Diggs, 1995b).
Comarostaphylis diversifolia is fairly
widely cultivated (Raven, 1966), but is the only species in the genus commonly
used horticulturally. McMinn (1949), Munz (1950), and Schmidt (1980)
give discussions of horticultural considerations. Several other species
have potential in this regard, particularly the red-flowered C. glaucescens.
Except as possible ornamentals, most of the species have little economic
value. However, there may be potential for their use in erosion control,
a particularly urgent problem in many areas of Mexico. Several
of the species seem ideal for this purpose, being long-lived, drought
tolerant, and tenacious in their soil-holding capability. Comarostaphylis
glaucescens is particularly noteworthy in this regard, having been
observed in severely eroded areas in Mexico (state), occupying mounds of
soil retained by the roots, while the surrounding
soil has been eroded away to a depth of several feet (Diggs, 1995b). Comarostaphylis discolor subsp. discolor has been used medicinally
(for insomnia) and its fruit is considered edible by some. Standley
(1924) stated that the fruit or leaves have narcotic properties: children
have been poisoned by the fruit, and the plant has been used for inducing
sleep or as a purgative. Two other taxa, C. arbutoides subsp. arbutoides and C. polifolia subsp. polifola, are also
said to have edible fruit (Diggs, 1995b).
COMAROSTAPHYLIS Zuccarini, Abh. math.-phys. Cl. Konigl.
Bayer. Akad. Wiss. 2: 331. 1837b; Humboldt, Bonpland
& Kunth, Nov. gen. sp. 3: 277-278, tab. 258. 1819 (as Arctostaphylos);
de Candolle, Prodr. 7: 584-585. 1839 (as Arctostaphylos);
Bentham, Pl. hartw. 44-45, 66. 1840 (as Arctostaphylos);
Martens & Galeotti, Bull. Acad. Roy. Soc. Bruxelles 9: 536-537.
1851 (as Arbutus and Arctostaphylos); Klotzsch, Linnaea
24: 73-78. 1851; Hemsley, Biol. centr.-amer., Bot. 2: 277-279.
1881 (as Arctostaphylos); Small, N. Amer. fl. 29(1): 33-102
(Comarostaphylis, pp. 85-91). 1914; Standley, Trees
shrubs Mexico, Contr. U.S. Natl. Herb. 23(4): 1091-1101 (as Arctostaphylos,
pp. 1094-1099). 1924; Standley & L. O. Williams, Flora
of Guatemala, Fieldiana, Bot. 24(VIII, no. 2): 88-127 (as Arctostaphylos,
pp. 91-94). 1966; Wilbur & Luteyn, Fl. Panama, Ann. Missouri
Bot. Gard. 65: 27-144 (as Arctostaphylos, pp. 34-37). 1978;
Henrickson, Madroño 28: 33-37. 1981; Diggs, Systematic
studies in the Arbuteae (Ericaceae, Vaccinioideae) including a revision
of the genus Comarostaphylis, Ph.D. diss., University of Wisconsin-Madison.
1981; Taxon 31: 725-727. 1982; Brittonia 38: 344-351.
1986b; Syst. Bot. 12: 586-600. 1987; Bull. Torrey Bot. Club
115: 203-208. 1988; Dorr & Diggs,
Brittonia 37: 378-381. 1985; Gonzalez Villarreal, Acta Bot. Mex.
9: 31-36. 1990a; Ericaceas de Jalisco, Mexico, Flora de Jalisco.
1990b; Diggs, Fl. Neotrop. Monogr. 66: 146-193. 1995.
Type species. Comarostaphylis arguta Zuccarini [=C. discolor (Hooker) Diggs]. Named for the clusters of Arbutus-like fruit;
from the Greek comaros, the Arbutus, and staphylis,
a cluster of grapes.
Arctostaphylos sect. Comarostaphylis (Zuccarini)
Gray, Geol Surv Calif., Bot. 1: 454. 1876.
Arctostaphylos subgen. Comarostaphylis (Zuccarini) Drude
in Engler & Prantl, Nat. Pflanzenfam. IV(1) 49. 1891.
Erect to spreading, or rarely trailing
or mat-forming evergreen or rarely facultatively drought-deciduous terrestrial
shrubs to small trees to 20 m, capable of sprouting after fire damage;
bark exfoliating, sometimes in patches, or peeling, shredding, or flaking;
indumentum varying from glabrous to densely pubescent by stalked, swollen-headed
glandular and/or eglandular trichomes. Leaves alternate, horizontally
oriented; lamina bifacial, plane to strongly revolute, usually coriaceous,
margin entire or toothed; pinnately nerved. Inflorescences
usually terminal, racemose, the racemes often clustered, or paniculate;
floral bracts solitary at base of pedicels; pedicels slender;
bracteoles 2, basal or sometimes to midway up the pedicel or at distal
tip. Flowers (4-)5-merous; calyx continuous with pedicel, persistent
in fruit; lobes much longer than the tube, equal or nearly so, separate
or slightly imbricate at anthesis, appressed to the corollas during flowering,
becoming spreading to reflexed in fruit; corollas cylindric to nearly
globose, greenish-white to white, pale yellow, pink, or red, glabrous or
pubescent, the lobes much shorter than the tube, imbricate before anthesis,
spreading or recurved; stamens equal; filaments dilated near
base, villous or rarely glabrous; anthers ovoid, dehiscence by two
pores/slits 1/4-1/3 to nearly 1/2 as long as the anther; ovary superior,
papillate, glabrous or pubescent, sessile on a weakly 10-lobed or ribbed,
hypogynous, disk-like nectary; ovules solitary in each locule, pendulous;
style straight, included or
slightly exserted, often persistent; stigma minute, slightly
capitate. Fruit drupaceous, warty, granular or papillate because
of the presence of multicellular papillae radiating more or less perpendicularly
outward, globose, juicy, nearly black to dark purple (red) at maturity;
nutlets united into a solid, spheroidal, thick-walled, stone-like
endocarp; seeds 1-1.5 mm long, solitary in each nutlet, pendulous by
a short, persistent, gray, cap-like funiculus; testa reticulate,
thick walled; embryo spathulate; chromosome number: n=13
(Hagerup, 1928; Schierenbeck & Diggs, unpublished data).
Comarostaphylis is restricted to North
and Central America, from southern California (Santa Barbara Co.), south
to Volcán de Chiriquí in western Panama, corresponding to
a latitudinal distribution from approximately 35°N to 9°N.
The center of diversity is in the tropical and subtropical uplands of Mexico,
with taxa extending south through the mountains into Central America, and
to the north, disjunct into the warm temperature zone of coastal southern
California. Of the 18 taxa, only the two subspecies of C. diversifolia and C. polifolia subsp. coahuilensis are completely extra-neotropical.
While there are several locally endemic taxa in Comarostaphylis -- e.g., C. sharpii, C. lanata, and C. discolor subsp. manantlanensis --this is not the typical situation. A number of taxa, such as C.
arbutoides subsp. arbutoides, C. discolor subsp. discolor,
and C. polifolia subsp. polifolia, are extremely widespread.
Others, including C. diversifolia, C. longifolia, and C.
polifolia subsp. minor, while not widespread, cover areas encompassing
several states and cannot be considered strictly local in occurrence.
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Key to Neotropical Species Back to Top
1. Mature fruit red; calyx lobes lanceolate or narrowly triangular;
inflorescences usually gray-tomentose; at
elevations of 600 m or
less; S California & N Baja California
............................. C.
diversifolia
2. Leaves rovolute; inflorescences 3.5-8
cm long; San Diego Co.,
California and
Baja California ........... C.
diversifolia subsp. diversifolia
2. Leaves plane; inflorescences 6-14
cm long; Santa Barbara & Los
Angeles Cos.,
California ..................... C.
diversifolia subsp. planifolia
1. Mature fruit black; calyx lobes usually triangular or
ovate-triangular, inflorescences glabrous
to variously pubescent,
but not gray-tomentose; at elevations above
1350 m; Mexico
(excluding Baja California) to Panama.
3. Leaves entire or rarely with a few
teeth.
4. Inflorescences
3.3 cm long or less; leaves often quite small
(frequently less than 4.3 cm long), plane; Sierra de Tapalpa
of Jalisco ...................................... C.
discolor subsp. macvaughii
4. Inflorescences
typically more than 3.3 cm long; leaf size
variable, leaves plane or revolute; Mexico (excluding Baja
California) to Panama.
5. Inflorescences canescent, paniculate with many branches;
leaf apices usually mucronate; N Hidalgo & N Queretero
........................................................................ C. mucronata
5. Inflorescences glabrous or variously pubescent but not
canescent, racemose or paniculate; leaf apices mucronate
or not; distribution various, but unknown from N Hidalgo
or N Queretero.
6. Leaves densely white tomentose below, revolute;
filaments sparingly villous; inflorescences densely
glandular hirsute; San Luis Potosí ..................... C.
lanata
6. Leaves glabrous or variously pubescent below but
without white tomentum, revolute or not; filaments
usually denselly villous (except C. sharpii);
inflorescences glandular hirsute or not,
distribution various.
7. Corolla red; leaves coriaceous or not, drought
deciduous or not.
8. Inflorescences racemose; filaments villous,
leaves thin, not coriaceous, sometimes
drought deciduous; often with a single
trunk, tree-like; San Luis Potosí to
Jalisco, Sinaloa, and Oaxaca ........ C.
glaucescens
8. Inflorescences paniculate; filaments
glabrous; leaves coriaceous, not drought
deciduous, typically shrubby; endemic to
Tamaulipas .......................................... C.
sharpii
7. Corollas white to pink; leaves coriaceous,
evergreen.
9. Largest leaves 6 cm or more long and 1.5 cm
or more wide; inflorescences paniculate,
much-branched; habitats usually mesic at
1350-3800 m; Chiapas to Panama .. C.
arbutoides
10. Leaves ferruginously tomentulose or
tomentose below; twigs, petioles, and
calyx lobes pubescent; Chiapas to
Panama.........C.
arbutoides subsp. arbutoides
10. Leaves glabrous below; twigs, petioles,
and calyx lobes glabrous; endemic to
Cordillera Central of Costa Rica
................. C.
arbutoides subsp. costaricensis
9. Largest leaves usually 6 cm or less long and
1.5 cm or less side; inflorescences racemose
or sometimes paniculate; habitats usually
xeric at 1500-2800 m; Chihuahua and Coahuila
south to Oaxaca ................................ C.
polifolia
11. Inflorescences and/or young branches and
petioles without glandular trichomes;
leaves plane; Nuevo Leon, Tamaulipas, and
San Luis Potosi ....... C.
polifolia subsp. minor
11. Inflorescences and often young branches
and petioles with glandular trichomes;
leaves usually revolute or folded; widespread.
12. Leaves usually strongly revolute;
ovary pubescent; twigs and
petioles usually glandular
hirsute; shrubs to 4(-6)m tall;
widespread ... C.
polifolia subsp. polifolia
12. Leaves usually not revolute, often
conduplicately folded at maturity;
ovary glabrous; twigs and petioles
usually without glandular
trichomes; shrubs to 2 m tall;
Coahuila .. C.
polifolia subsp. coahuilensis
3. Leaves usually distinctly serrulate,
serrate, or dentate.
13. Leaves
glabrous below; inflorescences glabrous or with
glandular trichomes .............................................. C. discolor
14. Largest leaves typically 7 cm or more long and 2 cm or
more wide; inflorescences glabrous or with glandular
trichomes; Jalisco across Mexico to Guatemala
............................................. C.
discolor subsp. discolor
14. Largest leaves typically 7 cm or less long and 2 cm or
less wide, often much smaller; inflorescences
glabrous; Sierra de Tapalpa, Jalisco ............
......................................... C.
discolor subsp. macvaughii
13. Leaves
with variable pubescence below;
inflorescences pubescent, trichomes eglandular or
glandular.
15. Inflorescences canescent; leaf apices
usually mucronate; N Hidalgo and N Queretero
................................................................ C. mucronata
15. Inflorescences glabrous to variously
pubescent, but not canescent; leaf apices
mucronate or not; distribution various but
unknown from Hidalgo or Queretero.
16. Largest leaves usually 8 cm or more
long, mostly lanceolate to elliptic;
Guerrero, Jalisco, Mexico (state), and
Michoacán.
17. Petioles and young twigs densely
glandular hirsute by long-stalked,
swollen-headed glandular
trichomes; inflorescences
glandular-hirsute; Mexico(state)
to Jalisco ..................................... C.
longifolia
17. Petioles without glandular
trichomes(or with a few small
scattered glandular trichomes);
inflorescences with eglandular or
glandular trichomes; Michoacán and
Jalisco ......................................... C.
discolor
18. Inflorescences with glandular
trichomes; Jalisco ...............
.......... C.
discolor subsp. manantlanensis
18. Inflorescences tomentulose to
tomentose, the trichomes
always eglandular; Michoacán
.................... C.
discolor subsp. rupestris
16. Largest leaves 7.5 cm or less long,
often ovate to obovate; Oaxaca and
Puebla ............................................. C.
spinulosa
19. Petioles and inflorescences with
only eglandular pubescence .....
....................... C.
spinulosa subsp. spinulosa
19. Petioles and inflorescences
glandular-hirsute ............
..................... C.
spinulosa subsp. glandulifera
This is a modified version of the taxonomic
treatment of the neotropical species of Comarostaphylis (Ericaceae)
by George M. Diggs, from "Ericaceae--Part II. The Superior-Ovaried
Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae
p.p.)." The full treatment including specimen citations may be see
in Flora Neotropica Monograph 66: 146-193
(Diggs, 1995b). This on-line synthesis is published with permission
of The New York Botanical Garden and George M. Diggs.
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