A NEW SPECIES OF IPOMOEA (CONVOLVULACEAE) FROM OAXACA, MEXICO

3 Pages·1992·1.4 MB·English

by  J Andrew Mcdonald

A
NEW
A
OF IPOMOEA (CONVOLVULACEAE)
SPECIES
FROM
OAXACA, MEXICO
ANDREW
McDonald
J.
Harvard Unhwsity
Herbaria
22
Avenue
Divinity
MA
Cambridge, 02138, U.S.
ABSTRACT
Recent collecting in Mexico has uncovered a novelty in Ipomoea (Convolvulaccae), gesnerioicles,
7.
&
from the arid Tehuacan valley of Oaxaca. closely related to bombycina Benth. Hook.,
It is 7.
section Bombycospermmn (Presl) Austin, but differs by producing basally terete stems, mostly
- cm - cm
terminal inflorescences, and larger, broadly urceolate corollas 3 3-5 long and 1.5 2
broad.
RESUMEN
Se reconoce una nueva especie del Valle de Tehuacan, Oaxaca, Ipomoea Parece ser
gesnerioicles
.
relacionacla con bombycma, sect. Bomhycosperrnimi^ de la cual se distingue por tallos basales
7.
— cm
rollizos, inflorescencias usualmente rerminales y corollas nrceoladas, 3 3-5 de largo.
Ipomoea McDonald
gesnerioides
sp. nov.
A — cm cm
1.5—2
Ipomoea bombycinae caule basale laeve terete ac coroUis 3 3-5 longis latis statim
diagnoscenda.
becoming
and
Vines lignescent, twining. Stems terete, initially erect straight,
twining and contorted, the hypocotyl swollen, succulent, smoothish, terete-
— cm cm
ellipsoid, 5 8 long, to 3 in diam., tan to gray, subdermally chlorophyl-
m
—
many
lous, bearing short shoots at the apex, ascending stems 0.5 3 long,
mm
—
new growth growth bark
2 12 in diam., pale green, villous, old tan,
- cm
membranous,
glabrous; internodes 2.5 long; roots fibrous. Leaves petio-
.5
1
— cm
late; petioles terete, 0.5 3-5 long, reduced on terminal, fertile branchlets,
some-
pLiberulent, villous or canescent; lamina broadly elliptic or occasionally
— —
cm cm
what rhombic, 2 8 long, 1.5 5 wide, dark green and puberulent
above, canescent below, primordially corrugate, margins entire, apex acute or
acuminate, base acute or subtruncate, occasionally subcordate on fertile branch-
venation pinnate. a scorpioid pseudoraceme comprised of re-
lets; Inflmxscence
duced, congested, single flowered cymes usually at the apex of fertile branches;
mm mm
— -
peduncles wanting; pedicels terete, 2 9 long, 0.5 in diam., green,
1
mm
5-7
- cm
puberulent; sepals subequal, ellipsoid, 1.5 long, wide, coria-
1 1
.
ceous, canescent or variably villous, margins entire, apex acute or obtuse; corolla
mm
mm
— 4-8
urceolate, basal portion of tube 6 8 long, in diam., distal portion
-
cm 1.5-2 cm
limb
dilating, 2.5 3 long, broad medially, pale green, flaring
173-175.
SIDA15(2): 1992
SiDA 1992
174
15(2):
FIG. shoots of Ipomoea based on the holotype. A. Flowering branch. B.
Fertile ges?7enoic/es
1.
Mature
Seed. C. fruiting branch.
— cm
abruptly, 2.5 3 wide, interplicae pale green, the exterior pubescent, plical
— cm
regions purple, glabrous; stamens subequal, 3.0 3-5 long, white, style sur-
mm;
passing androecium by 2 stigma bilobate, white. a broadly ellipsoid
ca. Fr////
mm
8-
- cm
capsule, locules 2, valves 4, tan, chartaceous, 1.1 1.3 long, 10 wide,
mm mm
— —
glabrous; seeds 4, ellipsoid, 3 —angled, 6 7 long, 3 3.5 wide, dark
brown, minutely puberulent with dense lanate tufts of hair along angle margins
cm
toward hilum, hairs white, to long.
1
W
Hwy
MEXICO.
Type: Oaxaov: 10.4 mi of Santiago Astata on 200, in scrub-deciduous
MEXU!,
forest, 9 Mar 1985, Luckaw 2605 (holotyfk: TEX!; isotyphs: USl).
&
Ipomoea gesnerioides most closely approaches hombycina Benth. Hook., type
/.
species oilpornoea sect. Bomhycospmnum (Presl) D. Austin, by the presentation of
McDonald, Ipomoea 175
-
cm
stem growth becomes
a swollen hypocotyl 3 wide, initially erect that later
1
somewhat
twining, corrugate leaves, scorpioid pseudoracemes, urceolate corol-
among
las, and densely lanate seeds. Ipomoea gesnerioides is unique all other Ipomoea
ofMexico, however, producing mostly terminal, scorpioid pseudoracemes and
in
- cm 1.5-2 cm
with
large (3 3.5 long, medially in diameter) urceolate corollas
a pale green and purple limb. Flowers of/, bombycina are generally born on axillary
cm
pseudoracemes (sometimes terminal), and corollas never exceed 2.5 in length
cm
The two
and in diameter. vegetative features of these species are also
1
distinctive, bombycina bearing a rough, furrowed, swollen hypocotyl, while the
/.
swollen hypocotyl of/, gesnerioides terete and relatively smooth. Both species are
is
restricted to the tropical deciduous forest of southern Mexico, bombycina
/.
occurring from Jalisco to Guerrero in tropical deciduous forest, and gesnerioides
/.
from type locality in the arid Tehuacan Valley of Oaxaca.
its