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FIELDIANA

Botany

Published by Field Museum of Natural History

Volume 34, No. 4 August 31, 1971

A New Species of Juniperus from Mexico

MARION T. HALL

THE MORTON ARBORETUM

LISLE, ILLINOIS

A new species of juniper was discovered southeast of Saltillo,

Coahuila, Mexico, while I was studying variability in Mexican

junipers and the ecology of the juniper-pinon association. This

work was done on a grant from the National Science Foundation,

NSF-GB-1860, under the administration of the Oklahoma Uni-

versity Research Institute, Norman, Oklahoma.

Juniperus saltillensis Hall, new species

Frutex 7 m., coma latior quam alta, multitruncus et ramosus humi vel supra

paululum; frons clara rava-viridis; virgae ravae et vestitae effusius ramulis

patulis recurvis fragiliter et concise vel languidis ad apices; cortex in infulis longis,

densis, mollibus, squameis, exterior albulus-ravus, interior rufus; matura folia

(cum) curti surculi squamis fere terna, solum decussata in ramulis extremis,

appressa denss et rotunda ad apicem obtusum, non implicantia nisi in aliquibus

ramulis extremis, 1-(1.5) 2 mm. longa, acuta ad obtusa, margines den tales

subtiliter, dense, nullo ordine, dorsalis glans ovata planaque ubi praesens, reperta

centraliter in vagina-folii; folia (cum) longis surculis 3-(4) 6 mm. longa, terna,

cum dorsalibus glandibus linearibus, elevatis, forma lacrimae, 1.5-(2) 4 mm.

longis; frutex dioicus, interdum monoicus; coni microsporangiati 2-(3) 3.5 mm.

longi, microsporophylla 8-(12), deltoidea, obtusus, dentales subtiliter, fere

carinata, carina altissima ad apicem, prope appressa et firme implicans, dorsalis

glans parva et obscura ad basem squamae, microsporangia 3-(4); bacae-coni

ovoidei latiores quam longi, 5-(6) 7 mm. longi, 4.5-(6) 8 mm. lati, clari albuli-

caerulei, glauci, rubri sub pruina, fibrosi et resinati cum copiosis saccis parvis

resinae, maturantes anno, megasporophylla 2 pares decussati, pingues et claudentes

bacam-conum in apice; semina (1) 2-3, ovoidea, sulcata, 4-5 mm. longa, circa 3

mm. lata, brunnea ubi matura hilum basali dimidium spatium ad apicem, flavum

vel eburnum, hilum et basis seminis glandulosum-puteosum.

Widely branching shrub to 7 m., crown broader than high, multi-stemmed and

branching at ground level or slightly above; foliage light grayish-green; twigs

gray and densely clothed with widely spreading branchlets crisply and shortly

recurved or drooping at the tips; bark in long thick, soft, flaky ribbons, outer

Library of Congress Catalog Card Number: 78-158360

Publication 1131 45

MAY 1 5 1972

MAY 1 7 1Q79 810L06Y LIBRARY

nHI | / W{£ I01BHR1M.I UAJP

46

FIELDIANA: BOTANY, VOLUME 34

FIG. 1. Herbarium specimens photographed to show branching types and bark

characters of Juniperus saltillensis. A, B, are one extreme and resemble branching

in J. flaccida. C, D, the other extreme of branching, resemble J. durangensis-

Photographs 1/9 X natural size.

whitish-gray, inner red-brown; adult short-shoot scale leaves mostly ternate,

decussate only on ultimate branchlets, closely appressed, thick and rounded to a

blunt tip, not overlapping except on some ultimate branchlets, l-(l.S)1 2 mm.

long, acutish to obtuse, finely, densely, irregularly toothed margins, dorsal gland

ovate and flat when present, located centrally on the leaf sheath; long-shoot

leaves 3 -(4) 6 mm. long, ternate, with linear, raised dorsal glands, teardrop-

shaped, 1.5-(2) 4 mm. long; dioecious, occasionally monoecious; microsporangiate

cones 2-(3) 3.5 mm. long, microsporophylls 8-(12), deltoid, obtuse, finely toothed,

usually keeled, the keel highest toward the tip, closely appressed and strongly

overlapping, dorsal gland small and inconspicuous at the base of the scale, micro-

sporangia 3-(4); berry-cones ovoid to wider than long, 5-(6) 7 mm. long, 4.5-(6)

8 mm. wide, bright whitish-blue, bloomy, wine-red beneath the bloom, fibrous

and highly resinous with abundant small resin sacs, ripening in one year, mega-

sporophylls two decussate pairs, fleshy and closing the berry-cone at the tip;

1 Values within parentheses throughout the description are average values

for the characters studied from the Saltillo population.

HALL: NEW SPECIES OF JUNIPERUS

47

FIG. 2. Camera lucida tracings of margins from long-shoot leaves. A,

Two tracings of leaf margins from J. durangensis; B, six tracings from J. saltillen-

sis; C, two tracings from J. flaccida. Tracings are of approximately 6 mm. from

tips toward bases of leaves. 10 X.

seeds (l)-2-3, ovoid, grooved, 4-5 mm. long, about 3 mm. wide, dark brown

when mature, basal hilum half the distance to the apex, yellowish or ivory, hilum

and base of seed gland-pitted.

Mexico: Coahuila. Eighteen miles southeast of Saltillo on

northeast-facing slopes of hills bordering Mexico Highway 57 at

6,700 ft. alt., Hall 66305-1 (holotype, F; OKL; MO; others).

Habitat. — Twenty-degree slope, in thin, rocky, limestone soil

weathered to gray containing abundant white limestone fragments,

associated with Juniperus deppeana Steud., Juniperus flaccida

Schlecht., and Pinus cembroides Zucc.

This new species is associated with Juniperus flaccida at the

lower edge of the pinon-juniper woodland, where a number of

mesquite-grassland species intermix. Mesquite, Ocotillo, and

Creosote Bush disappear at about 6,000 ft. but Desert Willow,

Lechuguilla, Yucca carnerosana, Rhus microphylla, Cercocarpus

montanus var. paucidentatus, Dasylirion texanum, Agarito, Opuntia

imbricata, Acacia constricta, and One-Seed Juniper intermix with

the lower portion of the pinon-juniper woodland at 6,200 ft. Heavy

grazing pressure from goats probably has extended this zone of

mixing. Juniperus deppeana forms the association with Pinus

cembroides beginning at 6,200 ft. and becoming nearly a pure stand

of pinon at 7,500 ft. A few specimens of Pseudotsuga menziesii

occur with pinon at 7,500 ft. From 6,700 to 7,200 ft. both Juniperus

flaccida and Juniperus saltillensis are frequent. At this location,

the population of J. saltillensis consisted of 17 trees and the major

associates listed above. I have observed and collected Juniperus

B

FIG. 3. Camera lucida tracings of marginal epidermal cells mid-distance

from leaf base to tip, from long-shoot leaves. A, six tracings from J. saltillensis;

B, two tracings from J. durangensis; C, two tracings from J. flaccida. The letters,

A, B, C, are oriented at basal ends of leaf segments. 180 X.

48

HALL: NEW SPECIES OF JUNIPERUS

49

saltillensis as far south as San Roberto, Nuevo Leon, about 60

miles south of Saltillo, Coahuila, (Hall 66524-31) and as far north-

west as Parras de la Fuente, Coahuila, on northeast slopes of the

same elongate range of hills in which the Saltillo population occurs.

Apparently, this species occurs in isolated stands between Parras

de la Fuente and Galeana, Nuevo Leon, but perhaps more widely.

Juniperus saltillensis is rather intermediate in many characters

between Juniperus flaccida and Juniperus durangensis Martinez.

In habit the new species, Juniperus saltillensis, resembles Juniperus

flaccida since the plants are multi-stemmed, usually broader than

tall, with leaf-bearing branches fan-shaped and generally broader

than long. In most technical details it approaches Juniperus

durangensis more closely. It is closely intermediate in so many

characters that one is tempted to consider Juniperus saltillensis

of hybrid origin, but the berry-cones are in no way intermediate,

relating closely to those of Juniperus durangensis. Clearly, Junip-

erus saltillensis is more variable within the individual plant — as

well as between plants — than are either of the other two species.

Juniperus saltillensis may be distinguished from Juniperus duran-

FIG. 4. Camera lucida tracings of leaf types; long-shoot leaves to the left

in each pair, short-shoot leaves to the right. A, two from J. durangensis; K,

eight from J. saltillensis; C, two from J. flaccida. 2.5 X.

50

FIELDIANA: BOTANY, VOLUME 34

FIG. 5. J. saltillensis. A, berry-cones, two ranks of decussate scales. B,

microsporangiate cones, note sharply keeled tips of microsporophylls. C, seeds,

note light colored hilum, resin pits, and grooves. 5 X.

gensis by its habit, its gray-green foliage, and its longer than wide,

bright blue, very bloomy berry-cones.

This new species, J. saltillensis, belongs in association with those

species of higher altitudes and more mesic habitats, J. monticola

Mart., J. standleyi Mart., and the poorly known species, J. jaliscana

Mart., and J. blancoi Mart. J. saltillensis is more xeric in habitat

than its closer relatives and has on the average fewer seeds per

berry-cone. It may be considered a taxon which links the poly-

HALL: NEW SPECIES OF JUNIPERUS

51

FIG. 6. J. durangensis. A, berry-cones, two ranks of decussate scales. B,

microsporangiate cones, note acute tips without keels on the microsporophylls.

C, seeds, note irregular shapes because of thin flanges. 5 X.

spermous, mesic species with the xeric monospermous ones. This

species is most attractive and should be considered for cultivation

in appropriate areas.

Figure 1 shows the extremes of characters from secondary

branches of Juniperus saltillensis. A and B show the broad form of

branching where often the vegetated portion is broader than long

and the angle of branching is wide. These traits correlate with a

52

FIELDIANA: BOTANY, VOLUME 34

FIG. 7. J. flaccida. A, berry-cones, three ranks of decussate scales showing

outlines of megasporophylls. B, microsporangiate cones with slender glands on

microsporophylls. C, seeds, irregular, deeply pitted and grooved, no flanges.

3 X.

thicker, softer, broad-stringy bark which is generally a light red-

brown color with a thin white bloom. The total aspect of these

trees is reminiscent of Juniperus flaccida though not in technical

details. C and D show the other extreme of branching where the

branches are longer than wide and with markedly acute angles.

The bark is dark, hard, narrow-stringy with scattered white to

gray bloom. These trees are similar in aspect to Juniperus duran-

gensis. All specimens seen have the pale green foliage with bright

glaucous bloom and homogeneous fruits and seeds.

HALL: NEW SPECIES OF JUNIPERUS 53

Figure 2 shows tracings of leaf margins as seen under a 10 X

hand lens, the pattern readily observable in the field. The teeth

of Juniperus durangensis leaves shown in Figure 2, A are more

uniformly spaced and at relatively right angles, i.e., more dentate,

while those of J. saltillensis (fig. 2, B) are clumped and serrate,

and those in J. flaccida (fig. 2, C) are fewer, less pronounced, and

more irregular. A look at Figure 3 will show the structural bases

of the marked differences in leaf margins. In J. saltillensis (fig. 3,

A) the teeth are seen to be outward projections of the proximal tips

of the marginal epidermal cells which form an acute angle to the

leaf mid-rib. In J. durangensis (fig. 3, B) the teeth are median

projections of cells which are either vertical or irregular in orienta-

tion, while in J. flaccida (fig. 3, C) the teeth are mere proximal

bumps on angled cells interrupted by occasional stretches of vertical

marginal cells without projections.

Figure 4 shows long-shoot and short-shoot leaf types for the

three species. In J. durangensis (fig. 4, A) the short-shoot leaves

show the pronounced "string-of -beads" effect; in J. saltillensis

(fig. 4, B) the most distinctive feature is the long, wide teardrop

gland of the long-shoot leaves. J. flaccida (fig. 4, C) is entirely

decussate in its leaf arrangement and with long slender glands.

Figures 5, 6, and 7 show the berry-cones, male-cones, and seeds

of the three species. The berry-cones show 2-ranks of decussate

scales in both J. durangensis and J. saltillensis and 3-ranks of

decussate scales in J. flaccida. In J. durangensis the berry-cones

are small, wider than long and angled toward a box-like shape; J.

saltillensis has slightly larger berry-cones which are nearly spherical

to slightly longer than wide, smooth, and very bloomy. In J.

flaccida the berry-cones are large, nearly twice larger than in J.

durangensis, longer than wide, smooth, with the cone scale outlines

or margins clearly showing. The microsporangiate cones are

eglandular in J. durangensis and J. saltillensis but with narrow,

long glands in J. flaccida. In «/. saltillensis the cone scales are

strongly keeled toward the tip, either rounded abruptly or mucro-

nate, while in J. durangensis they are not keeled but merely rounded

and have acute tips.

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