Canyon Ironwood

Ostrya knowltonii occurs sporadically throughout the arid Southwest, including both rims of the Grand Canyon. On the basis of morphology and phytogeography, it appears to be more closely allied with Ostrya in mountainous western Mexico than with the eastern O . virginiana .

Trees , to 9 m; crowns open, narrowly rounded. Bark brownish gray, broken into narrow vertical scales or rather ragged strips. Twigs sparsely to moderately pubescent, often with stipitate glands. Leaves: petiole covered with stipitate glands. Leaf blade ovate or broadly ovate-elliptic to broadly elliptic or nearly orbiculate, 2.5--6.5 × 1.5--5 cm, base narrowly rounded to cordate or cuneate, margins sharply and unevenly doubly serrate, apex acute; surfaces abaxially pubescent, especially on veins. Inflorescences: staminate catkins 2--3 cm; pistillate catkins 0.6--1 cm. Infructescences 2.5--4 × 1.8--2.5 cm; bracts 1--1.8 × 0.5--1 cm.

Ariz., N.Mex., Tex., Utah.

Flowering late spring.

Streamsides and rocky slopes in moist canyons; 1200--2400m.

Ostrya baileyi Rose

More info for the term: tree

Knowlton's hophornbeam
ironwood
western hophornbeam
woolly hophornbeam
wolf hophornbeam


TAXONOMY:
The scientific name of Knowlton's hophornbeam is Ostrya knowltonii
Coville (Betulaceae) [9,10,7,23]. There are no recognized infrataxa.


LIFE FORM:
Tree

FEDERAL LEGAL STATUS:
No special status

OTHER STATUS:
NO-ENTRY





DISTRIBUTION AND OCCURRENCE
SPECIES: Ostrya knowltonii
GENERAL DISTRIBUTION:
Knowlton's hophornbeam is found in southeastern Utah, northern Arizona,
southeastern New Mexico (in the Guadalupe and Sacramento mountains in
Eddy County), and northern Trans-Pecos Texas. It is not a common tree
and its occurrence is sporadic even in these areas [9,10,18,23].

More info for the term: tree

Knowlton's hophornbeam is found in southeastern Utah, northern Arizona,
southeastern New Mexico (in the Guadalupe and Sacramento mountains in
Eddy County), and northern Trans-Pecos Texas. It is not a common tree
and its occurrence is sporadic even in these areas [9,10,18,23].



Distribution of Knowlton's hophornbeam. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, July 20] [21].

More info for the terms: association, forest, mesic, xeric

Knowlton's hophornbeam is commonly found in oak (Quercus spp.) woodlands,
pinyon (Pinus spp.)-juniper (Juniperus spp.) woodlands, and lower
ponderosa pine (Pinus ponderosa) forest zones [9]. In Texas it is a
component of the gray oak (Quercus grisea)-true pinyon (Pinus
edulis)-alligator juniper (Juniperus deppeana) association at 5,000 to
7,000 feet (1,524-2,133 m) and the ponderosa pine-Douglas fir
(Pseudotsuga menziesii) association at 6,000 to 7,500 feet (1,828-2,286
m). In Texas it is also associated with Texas madrone (Arbutus
texana), southwestern white pine (Pinus strobiformis), chinkapin oak (Q.
muehlenbergii), and bigtooth maple (Acer grandidentatum) [18]. In
deciduous canyon woodlands of Guadalupe Mountains National Park, Texas,
Knowlton's hophornbeam will increasingly replace wavyleaf oak (Q.
undulata), alligator juniper, Riogrande cottonwood (Populus deltoides
ssp. wislizenii) and little walnut (Juglans microcarpa) as the moisture
gradient goes from xeric to mesic. Knowlton's hophornbeam is replaced by
bigtooth maple and chinkapin oak, especially on upper terraces, around
springs and in canyonheads [6,13].

More info for the term: tree

Tree

Hophornbeam species (Ostrya spp.) suffer from few insect pests or
diseases, and none of these are regarded to be of economic importance
[4].

More info on this topic.

More info for the term: fruit

Knowlton's hophornbeam flowers are produced from March through May before
or with the leaves [15,23]. The fruit of hophornbeam species matures
and is dispersed during the same season as pollination. In most
hophornbeam species, the staminate catkins are produced the growing
season before anthesis and are exposed during the winter. The
pistillate catkins develop in the spring with the new shoots, with
anthesis occurring as the leaves are forming [4].

The scientific name of Knowlton's hophornbeam is Ostrya knowltonii
Coville (Betulaceae) [9,10,7,23]. There are no recognized infrataxa.

Ostrya chisosensis, common name Big Bend hop-hornbeam or Chisos hop-hornbeam, is a plant species endemic to Texas. It is known only from the Chisos Mountains inside Big Bend National Park, in Brewster County, although related populations in northern Chihuahua have not been studied in detail and may be the same species. It grows along streambanks and on the walls of canyons.

Ostrya chisosensis is a tree up to 12 m tall. Bark splits into narrow vertical strips. Leaves broadly elliptic to lanceolate, lacking glandular hairs. Staminate (male) catkins are 3.5–5 cm long.