Index of Species Information
SPECIES: Ostrya knowltonii
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| Knowlton's hophornbeam. Image by John Ruter, University of Georgia, Bugwood.org. |
Introductory
SPECIES: Ostrya knowltonii
AUTHORSHIP AND CITATION:
Tesky, Julie L. 1994. Ostrya knowltonii. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
https://www.fs.usda.gov/database/feis/plants/tree/ostkno/all.html [].
Revisions:
Images were added on 20 July 2018.
ABBREVIATION:
OSTKNO
SYNONYMS:
Ostrya baileyi Rose [9,23]
NRCS PLANT CODE:
OSKN
COMMON NAMES:
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].
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| Distribution of Knowlton's hophornbeam. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, July 20] [21]. |
ECOSYSTEMS:
FRES21 Ponderosa pine
FRES32 Texas savanna
FRES35 Pinyon - juniper
STATES:
AZ NM UT TX
BLM PHYSIOGRAPHIC REGIONS:
12 Colorado Plateau
13 Rocky Mountain Piedmont
KUCHLER PLANT ASSOCIATIONS:
K019 Arizona pine forest
K023 Juniper - pinyon woodland
K031 Oak - juniper woodlands
K032 Transition between K031 and K037
K086 Juniper - oak savanna
SAF COVER TYPES:
210 Interior Douglas-fir
237 Interior ponderosa pine
239 Pinyon - juniper
241 Western live oak
SRM (RANGELAND) COVER TYPES:
504 Juniper-pinyon pine
733 Juniper-oak
735 Sideoats grama-sumac-juniper
HABITAT TYPES AND PLANT COMMUNITIES:
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].
MANAGEMENT CONSIDERATIONS
SPECIES: Ostrya knowltonii
WOOD PRODUCTS VALUE:
Knowlton's hophornbeam wood is thin, fine grained, hard, tough, and
durable [4,23]. It is occasionally used for fuel or posts [23].
Because of its density the wood of hophornbeam (Ostrya spp.) can be used
for tool handles, mallet heads, and other hard wooden objects [4].
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Several species of breeding birds use canyonland habitats where Knowlton
hophornbeam occurs [12].
PALATABILITY:
NO-ENTRY
NUTRITIONAL VALUE:
NO-ENTRY
COVER VALUE:
NO-ENTRY
VALUE FOR REHABILITATION OF DISTURBED SITES:
NO-ENTRY
OTHER USES AND VALUES:
NO-ENTRY
OTHER MANAGEMENT CONSIDERATIONS:
Hophornbeam species (Ostrya spp.) suffer from few insect pests or
diseases, and none of these are regarded to be of economic importance
[4].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Ostrya knowltonii
GENERAL BOTANICAL CHARACTERISTICS:
Knowlton's hophornbeam is a native, deciduous, small tree 10 to 40 feet
(3-12 m) tall with a 6- to 18-inch (15.2-45.7 cm) trunk diameter [9,23].
The trunk is usually short and divided into a number of slender, crooked
branches to form a round-topped crown [23]. The leaves are 1 to 2.5
inches (2.5-6.3 cm) long and short-pointed or rounded at the apex
[7,9,23]. The twigs are slender, tomentose at first to glabrous and
lustrous later [l9,23]. The bark is 0.125 inch (0.31 cm) thick,
shallowly furrowed and breaking into loose, small scales 1 to 2 inches
(2.5-5 cm) long [23].
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| Knowlton's hophornbeam leaves and fruit. Image by Steven Katovich, USDA Forest Service, Bugwood.org. |
Male and female flowers are in catkins [9,23]. The staminate catkins
form singly or in groups of two to three at the tips of the previous
year's branches. They are slender, cylindrical, pendulous and 0.5 to
1.25 inch (1.3-3.2 cm) long [15,23]. The pistillate catkins are about
0.25 inch (0.6 cm) long, generally with two flowers in the axil of each
bract [23]. The fruit is a compressed ovoid nutlet [4]. The nutlet is
about 0.25 inch (0.6 cm) long, solitary, and sessile [23].
RAUNKIAER LIFE FORM:
Phanerophyte
REGENERATION PROCESSES:
Knowlton's hophornbeam reproduces by seed. The flowers are wind
pollinated and the fruit is wind dispersed [14]. Germination is epigeal
[4]. Unless seeds are sown soon after maturity or are stratified, they
will not germinate until the second year [23]. No specific information
was available on germination rates or viability of Knowlton's hophornbeam
seeds; however, information is available on eastern hophornbeam (Ostrya
virginiana) [17]. Eastern hophornbeam seeds usually germinate in the
spring the year after they are shed. Germination capacity of eastern
hophornbeam seed is 27 to 65 percent [11]. Eastern hophornbeam trees do not
produce seeds abundantly until they are about 25 years old [17].
Knowlton's hophornbeam can be regenerated by grafting [23]. Other species
of hophornbeam will sprout from the stump if cut or burned; however, no
specific information was available regarding the ability of Knowlton
hophornbeam to do so [11].
SITE CHARACTERISTICS:
Knowlton's hophornbeam is commonly found on sunny, dry, well-drained sites
in mountains and canyons and at the bases of monoliths in sandstone
areas [15,22,23,24]. Knowlton's hophornbeam commonly occurs between 4,200
and 7,000 feet (1,280-2,133 m) in elevation [7,9,15,23,24].
SUCCESSIONAL STATUS:
Specific information regarding Knowlton's hophornbeam's successional
status was not available in the literature. Eastern hophornbeam
typically occurs in late seral to climax forests. It is shade tolerant
and will reproduce well under full shade [11]. How closely this applies
to Knowlton's hophornbeam is unknown.
SEASONAL DEVELOPMENT:
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].
FIRE ECOLOGY
SPECIES: Ostrya knowltonii
FIRE ECOLOGY OR ADAPTATIONS:
Specific information was not available regarding the fire ecology and
adaptations of Knowlton's hophornbeam as of 1994. Knowlton's hophornbeam
may sprout after top-kill by fire, as do other species of hophornbeam [11].
Knowlton's hophornbeam probably also colonizes burned sites via
wind-dispersed seeds. Pinyon-juniper communities where Knowlton
hophornbeam commonly occurs have historically burned every 10 to 30
years. Where livestock grazing has reduced grass cover and accelerated
erosion, fire frequency has decreased [25].
FIRE REGIMES:
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find Fire Regimes".
POSTFIRE REGENERATION STRATEGY:
NO-ENTRY
FIRE EFFECTS
SPECIES: Ostrya knowltonii
IMMEDIATE FIRE EFFECT ON PLANT:
Information was not available regarding the immediate effects of fire on
Knowlton's hophornbeam; however, this tree is probably top-killed or
killed by most fires.
PLANT RESPONSE TO FIRE:
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS:
NO-ENTRY
REFERENCES
SPECIES: Ostrya knowltonii
REFERENCES:
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[434]
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network (PIN) data base: Colorado, Montana, North Dakota, Utah, and
Wyoming. FWS/OBS-83/86. Washington, DC: U.S. Department of the Interior,
Fish and Wildlife Service. 786 p. [806]
3. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. [905]
4. Furlow, John J. 1990. The genera of Betulaceae in the southeastern
United States. Journal of the Arnold Arboretum. 71(1): 1-67. [15644]
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1977. Vegetation and environmental features of forest and range
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6. Gehlbach, Frederick R. 1979. Biomes of the Guadalupe Escarpment:
vegetation, lizards, and human impact. In: Genoways, Hugh H.; Baker,
Robert J., eds. Biological investigations in the Guadalupe Mountains
National Park: Proceedings of a symposium; 1975 April 4-5; Lubbock, TX.
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Elizabeth. 1960. Arizona flora. 2d ed. Berkeley, CA: University of
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of the conterminous United States. Special Publication No. 36. New York:
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species of New Mexico and Arizona. Agriculture Handbook No. 9.
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[20330]
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and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of
Agriculture, Forest Service. 375 p. [2952]
11. Metzger, F. T. 1990. Ostrya virginiana (Mill.) K. Koch eastern
hophornbeam. In: Burns, Russell M.; Honkala, Barbara H., technical
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selected woodlands of the southern Guadalupe Mountains, Texas. In:
Genoways, Hugh H.; Baker, Robert J., eds. Biological investigations in
the Guadalupe Mountains National Park: Proceedings of a symposium; 1975
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13. Northington, David K.; Burgess, Tony L. 1979. Summary of the vegetative
zones of the Guadalupe Mountains National Park, Texas. In: Genoways,
Hugh H.; Baker, Robert J., eds. Biological investigations in the
Guadalupe Mountains National Park: Proceedings of a symposium; 1975
April 4-5; Lubbock, TX. Proceedings and Transactions Series No. 4.
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Big Bend and Guadalupe Mountains National Parks. Big Bend National Park,
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geography. Oxford: Clarendon Press. 632 p. [2843]
17. Schopmeyer, C. S.; Leak, W. B. 1974. Ostrya virginiana (Mill.) K.Koch
eastern hophornbeam. In: Schopmeyer, C. S., ed. Seeds of woody plants in
the United States. Agriculture Handbook No. 450. Washington, DC: U.S.
Department of Agriculture, Forest Service: 564-565. [7718]
18. Simpson, Benny J. 1988. A field guide to Texas trees. Austin, TX: Texas
Monthly Press. 372 p. [11708]
19. Stickney, Peter F. 1989. Seral origin of species originating in northern
Rocky Mountain forests. Unpublished draft on file at: U.S. Department of
Agriculture, Forest Service, Intermountain Research Station, Fire
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20. Swan, Frederick R., Jr. 1970. Post-fire response of four plant
communities in south-central New York state. Ecology. 51(6): 1074-1082.
[3446]
21. U.S. Department of Agriculture, Natural Resources Conservation Service. 2018.
PLANTS Database, [Online]. U.S. Department of Agriculture, Natural Resources
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Austin, TX: University of Texas Press. 1104 p. [7707]
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