Monographs Details:
Authority:
Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560. (Published by NYBG Press)
Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560. (Published by NYBG Press)
Family:
Ericaceae
Ericaceae
Description:
Species Description - Trees, or large shrubs, 2-6(-10 or 15) m tall. Bark light or more often dark gray, rough, appearing checkered with isodiametric, rectangular segments or plates 1-2 cm long and 2/3 as wide on the bole and limbs of approximately 6 years and older; twigs of the previous seasons with outer bark shed in small, roughened flakes; vestiture of all axes of the current season’s growth, including petioles [where most apparent] and leaf surfaces, usually with hairs of 2 kinds: 1) the longer up to 4.7(-5.2) mm, averaging ca 2.5 mm, flexuous, often straight and disposed more or less at right angles, rusty-colored when young, becoming clear, with reddish or yellowish glandular tips, the glands short clavate, rarely spherical, often infected by a fungal anamorph, Sirosporium antenniforme (Berkeley & Curtis) Bubak & Serebrianikow, that renders the glands black and gives the specimens a speckled or dotted appearance; 2) the shorter hairs glandless, curly, producing a thinly tomentose indument. Leaves olive-green above, markedly lighter green beneath, ovate or elliptic, (2-)4.5-6.5(-9) × (1.5-)2-3(-5.5) cm, the longer and wider blades on sterile shoots; base variably tapered, rounded, truncate, or slightly cordate, apex acute, often with a small (1-2 mm) cusp or short-acuminate tip (rarely obtuse and lacking a cusp); margins finely serrate, especially on sterile shoots (coarsely toothed on sprouts), sometimes minutely serrate or smooth on fertile shoots; upper surface usually slightly glossy, especially when fresh, glabrous except along the midrib where the glandular hairs shorter than on the young twigs, diminishing in size and density distally; lower surface fleetingly floccose on newly emerged leaves, tomentum sometimes persisting on blades of sterile shoots, then tan or brown; petioles 1.2-2.7 cm long, conspicuously glandular hairy. Inflorescence a terminal cluster of racemes, these sometimes densely branched, axes, including the pedicels, densely glandular hairy. Flowers borne obliquely erect on slender, glandular-hairy, accrescent pedicels up to 1.1 cm long at anthesis, subtended by a dark reddish bract, ca. 2.8 mm long, enclosing two smaller bracteoles; calyx at first cupulate, lobes scarious-margined, obtuse or rounded at the apex; corolla creamy white or yellowish, drying to pale yellow or tan, 5.2-6.3(-7.2) mm long, developing a post-anthesis circumferential dimple at about midway its length; corolla lobes imbricate with auriculate margins; stamens with anthers 1.3-1.5 mm long, bearing a pair of very finely tuberculate spurs 1/3-1/2 the length of the sacs; ovary producing 2 to several ovules per locule. Fruit to 8.5 mm diam.; seeds averaging 2.1 mm long.
Species Description - Trees, or large shrubs, 2-6(-10 or 15) m tall. Bark light or more often dark gray, rough, appearing checkered with isodiametric, rectangular segments or plates 1-2 cm long and 2/3 as wide on the bole and limbs of approximately 6 years and older; twigs of the previous seasons with outer bark shed in small, roughened flakes; vestiture of all axes of the current season’s growth, including petioles [where most apparent] and leaf surfaces, usually with hairs of 2 kinds: 1) the longer up to 4.7(-5.2) mm, averaging ca 2.5 mm, flexuous, often straight and disposed more or less at right angles, rusty-colored when young, becoming clear, with reddish or yellowish glandular tips, the glands short clavate, rarely spherical, often infected by a fungal anamorph, Sirosporium antenniforme (Berkeley & Curtis) Bubak & Serebrianikow, that renders the glands black and gives the specimens a speckled or dotted appearance; 2) the shorter hairs glandless, curly, producing a thinly tomentose indument. Leaves olive-green above, markedly lighter green beneath, ovate or elliptic, (2-)4.5-6.5(-9) × (1.5-)2-3(-5.5) cm, the longer and wider blades on sterile shoots; base variably tapered, rounded, truncate, or slightly cordate, apex acute, often with a small (1-2 mm) cusp or short-acuminate tip (rarely obtuse and lacking a cusp); margins finely serrate, especially on sterile shoots (coarsely toothed on sprouts), sometimes minutely serrate or smooth on fertile shoots; upper surface usually slightly glossy, especially when fresh, glabrous except along the midrib where the glandular hairs shorter than on the young twigs, diminishing in size and density distally; lower surface fleetingly floccose on newly emerged leaves, tomentum sometimes persisting on blades of sterile shoots, then tan or brown; petioles 1.2-2.7 cm long, conspicuously glandular hairy. Inflorescence a terminal cluster of racemes, these sometimes densely branched, axes, including the pedicels, densely glandular hairy. Flowers borne obliquely erect on slender, glandular-hairy, accrescent pedicels up to 1.1 cm long at anthesis, subtended by a dark reddish bract, ca. 2.8 mm long, enclosing two smaller bracteoles; calyx at first cupulate, lobes scarious-margined, obtuse or rounded at the apex; corolla creamy white or yellowish, drying to pale yellow or tan, 5.2-6.3(-7.2) mm long, developing a post-anthesis circumferential dimple at about midway its length; corolla lobes imbricate with auriculate margins; stamens with anthers 1.3-1.5 mm long, bearing a pair of very finely tuberculate spurs 1/3-1/2 the length of the sacs; ovary producing 2 to several ovules per locule. Fruit to 8.5 mm diam.; seeds averaging 2.1 mm long.
Discussion:
The vernacular name "madrono" is used frequently for Arbutus tessellata, as it is for other species of Arbutus. Additional names recorded in herbaria are madrono negro (Duges J89A, GH); madrono chino {Hewitt 28, GH); and in Tepehuan (SW Chihuahua), eto-pi-da-mi-ha-rao-da-fam-i (Hartman 526, GH). The epithet tessellata refers to the characteristic of the bark that is retained and soon invests the trunk with a checkered appearance. Other Arbutus species typically shed the bark over most of the length of the bole and limbs. The trunk of A. tessellata resembles that of the distinctive Juniperus deppeana Steudel, the alligator-bark juniper, of the Chihuahuan Desert.Arbutus tessellata seems closely related to the partially sympatric A. arizonica, which extends beyond our range into northwestern Mexico and adjacent United States. The leaves of both species have a broad range of leaf-base shapes, although in A. arizonica tapered leaf bases prevail, while in A. tessellata the tapered condition represents the extreme. The most striking characteristic shared by the two species, however, is in the nature of their bark. So far as is known, these two and A. madrensis among the New World Arbutus are the only species to retain their bark from an early age, resulting in boles and limbs that possess checkered bark as described above.Herbarium specimens of Arbutus tessellata have quite consistently been determined as A. glandulosa Martens & Galeotti. The availability and familiarity of the descriptive epithet "glandulosa" and the wording in the protologue, "ramis petiolis pedunculisque hirsuto-tomentosis, pilis fuscis glanduliferis" (my emphasis), have led to its use for nearly all specimens that have glandular hairs on petioles and inflorescence branches. I have been fortunate enough to examine the lectotype of A. glandulosa Martens & Galeotti (BR), and have concluded that it represents a glandular-haired variant of the widespread and polymorphic A. xalapensis. On the basis of the glandular hairs alone, A. tessellata differs from glandular-haired specimens of A. xalapensis in a quantitative way in that the gland-bearing hairs of the latter rarely reach 1.5 mm long and are often scarcely longer than the companion non-glandular hairs. The gland-bearing hairs of A. tessellata consistently average at least 2.5 mm long or longer and may be up to 5.2 mm long, and on any given specimen many hairs will reach or exceed 3.5 mm (see Fig. 3). Despite this rather clear distinction, the name A. glandulosa will perhaps persist in being used, due to its widespread familiarity. To facilitate acceptance of its reduction to synonymy with A. xalapensis, I think it is worthwhile to draw a direct comparison between the “glandulosa”-type plants (based on the characteristics visible on the lectotype and other collections matching it) and A. tessellata. Table I summarizes these comparisons.Field identification of Arbutus tessellata is easily accomplished on observing the spreading, elongated glandular hairs. Also, the checkered bark that is retained on older twigs and the main axes will usually serve to distinguish it from A. xalapensis.
The vernacular name "madrono" is used frequently for Arbutus tessellata, as it is for other species of Arbutus. Additional names recorded in herbaria are madrono negro (Duges J89A, GH); madrono chino {Hewitt 28, GH); and in Tepehuan (SW Chihuahua), eto-pi-da-mi-ha-rao-da-fam-i (Hartman 526, GH). The epithet tessellata refers to the characteristic of the bark that is retained and soon invests the trunk with a checkered appearance. Other Arbutus species typically shed the bark over most of the length of the bole and limbs. The trunk of A. tessellata resembles that of the distinctive Juniperus deppeana Steudel, the alligator-bark juniper, of the Chihuahuan Desert.Arbutus tessellata seems closely related to the partially sympatric A. arizonica, which extends beyond our range into northwestern Mexico and adjacent United States. The leaves of both species have a broad range of leaf-base shapes, although in A. arizonica tapered leaf bases prevail, while in A. tessellata the tapered condition represents the extreme. The most striking characteristic shared by the two species, however, is in the nature of their bark. So far as is known, these two and A. madrensis among the New World Arbutus are the only species to retain their bark from an early age, resulting in boles and limbs that possess checkered bark as described above.Herbarium specimens of Arbutus tessellata have quite consistently been determined as A. glandulosa Martens & Galeotti. The availability and familiarity of the descriptive epithet "glandulosa" and the wording in the protologue, "ramis petiolis pedunculisque hirsuto-tomentosis, pilis fuscis glanduliferis" (my emphasis), have led to its use for nearly all specimens that have glandular hairs on petioles and inflorescence branches. I have been fortunate enough to examine the lectotype of A. glandulosa Martens & Galeotti (BR), and have concluded that it represents a glandular-haired variant of the widespread and polymorphic A. xalapensis. On the basis of the glandular hairs alone, A. tessellata differs from glandular-haired specimens of A. xalapensis in a quantitative way in that the gland-bearing hairs of the latter rarely reach 1.5 mm long and are often scarcely longer than the companion non-glandular hairs. The gland-bearing hairs of A. tessellata consistently average at least 2.5 mm long or longer and may be up to 5.2 mm long, and on any given specimen many hairs will reach or exceed 3.5 mm (see Fig. 3). Despite this rather clear distinction, the name A. glandulosa will perhaps persist in being used, due to its widespread familiarity. To facilitate acceptance of its reduction to synonymy with A. xalapensis, I think it is worthwhile to draw a direct comparison between the “glandulosa”-type plants (based on the characteristics visible on the lectotype and other collections matching it) and A. tessellata. Table I summarizes these comparisons.Field identification of Arbutus tessellata is easily accomplished on observing the spreading, elongated glandular hairs. Also, the checkered bark that is retained on older twigs and the main axes will usually serve to distinguish it from A. xalapensis.
Distribution and Ecology: From about 27º22'N in the state of Chihuahua, southward through the Sierra Madre Occidental into Jalisco, thence eastward along the northern slopes of the Sierra Volcanica Transversal to extreme western Veracruz, the southernmost locality in the state of Mexico, SW of Distrito Federal, about 18º45'N (Fig. 4). In the montane zone with Pinus and Quercus, 1500-2850 m. Flowering as early as November, reaching a peak in March; fruiting (February-)April-June. No specimens seen in flower nor fruit during August and September.
Distribution:
Mexico North America| Chihuahua Mexico North America| Durango Mexico North America| Guanajuato Mexico North America| Hidalgo Mexico North America| Jalisco Mexico North America| Nayarit Mexico North America| México Mexico North America| Querétaro Mexico North America| San Luis Potosí Mexico North America| Sinaloa Mexico North America| Tlaxcala Mexico North America| Veracruz Mexico North America|
Mexico North America| Chihuahua Mexico North America| Durango Mexico North America| Guanajuato Mexico North America| Hidalgo Mexico North America| Jalisco Mexico North America| Nayarit Mexico North America| México Mexico North America| Querétaro Mexico North America| San Luis Potosí Mexico North America| Sinaloa Mexico North America| Tlaxcala Mexico North America| Veracruz Mexico North America|
Common Names:
madroño, madroño negro, madroño chino, Et'-pi-da-mi-ha-rao-da-fam-i
madroño, madroño negro, madroño chino, Et'-pi-da-mi-ha-rao-da-fam-i