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Plants of Caddo Lake National Wildlife Refuge (NWR) in Texas. Published by the U.S. Fish & Wildlife Service (USFWS).
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Prepared in cooperation with the U.S. Fish and Wildlife Service
A Comprehensive List and Photographic Collection of the
Vascular Flora of Caddo Lake National Wildlife Refuge,
Texas, March 2011–March 2012
Data Series 854
U.S. Department of the Interior
U.S. Geological Survey
Cover, Caddo Lake National Wildlife Refuge, Texas, August 2011.
A Comprehensive List and Photographic
Collection of the Vascular Flora of Caddo
Lake National Wildlife Refuge, Texas,
March 2011–March 2012
By Larry Allain
Prepared in cooperation with the U.S. Fish and Wildlife Service
Data Series 854
U.S. Department of the Interior
U.S. Geological Survey
U.S. Department of the Interior
SALLY JEWELL, Secretary
U.S. Geological Survey
Suzette M. Kimball, Acting Director
U.S. Geological Survey, Reston, Virginia: 2014
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Suggested citation:
Allain, Larry, 2014, A comprehensive list and photographic collection of the vascular flora of Caddo Lake National
Wildlife Refuge, Texas, March 2011–March 2012: U.S. Geological Survey Data Series 854, 41 p., http://dx.doi.
org/10.3133/ds854.
ISSN 2327-638X (online)
iii
Contents
Abstract ...........................................................................................................................................................1
Introduction ....................................................................................................................................................1
Description of Study Area ............................................................................................................................2
Methods ..........................................................................................................................................................2
Results .............................................................................................................................................................2
Discussion .......................................................................................................................................................9
Summary .......................................................................................................................................................11
Acknowledgments .......................................................................................................................................11
References Cited .........................................................................................................................................11
Photograph Collection (available at http://pubs.usgs.gov/ds/854/)
Figures
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Map showing location of Caddo Lake National Wildlife Refuge, Texas ..............................3
Photograph showing chambered pith of black walnut (Juglans nigra), an
example of diagnostic plant characters photographed during this project at
Caddo Lake National Wildlife Refuge, Texas ...........................................................................4
Photographs showing the differences in leaf form of two varieties of Taxodium
distichum occurring on Caddo Lake National Wildlife Refuge, Texas .................................5
Photograph showing pine-hardwood forest predominant on slopes and other
well-drained sites in Caddo Lake National Wildlife Refuge, Texas ......................................6
Photograph showing bottomland hardwoods dominated by baldcypress
(Taxodium distichum var. distichum) along drainages and in frequently flooded
parts of Caddo Lake National Wildlife Refuge, Texas ............................................................6
Photograph showing Chinese tallow tree (Triadica sebifera), an invasive
nonnative species that is currently controlled by refuge management at Caddo
Lake National Wildlife Refuge, Texas ........................................................................................7
Photograph showing staff of Caddo Lake National Wildlife Refuge, Texas, using
herbicide to treat small Chinese tallow trees (Triadica sebifera) before these
nonnative, highly invasive trees can bear seeds and colonize additional area ................8
Photograph showing an invasive understory shrub, sacred bamboo (Nandina
domestica), that was collected on a small outholding of Caddo Lake National
Wildlife Refuge, Texas, north of Texas Farm to Market Road 2198 (FM 2198) ....................9
Photograph showing giant salvinia (Salvinia molesta), considered one of the
world’s worst aquatic pests ........................................................................................................9
Photograph showing a three-toed box turtle (Terrapene carolina triunguis), so
named because of the number of toes on the back feet, at Caddo Lake National
Wildlife Refuge, Texas ...............................................................................................................10
Photograph showing American lady butterfly (Vanessa virginiensis) nectering
on the flowers of groovestem Indian plantain (Arnoglossum plantagineum) on a
roadside along the Auto Route in Caddo Lake National Wildlife Refuge, Texas .............10
iv
Tables
1.
Comprehensive list of vascular plants identified at Caddo Lake National Wildlife
Refuge, Texas, March 2011–March 2012 ................................................................................12
2. List of nonnative plant species occurring at Caddo Lake National Wildlife Refuge,
Texas, March 2011–March 2012 ...............................................................................................28
3. List of vascular plant species found at Caddo Lake National Wildlife Refuge,
Texas, March 2011–March 2012, with food value for wildlife .............................................30
Conversion Factors
Inch/Pound to SI
Multiply
By
To obtain
Length
mile (mi)
1.609
kilometer (km)
SI to Inch/Pound
Multiply
By
To obtain
Area
hectare (ha)
2.471
acre
A Comprehensive List and Photographic Collection of the
Vascular Flora of Caddo Lake National Wildlife Refuge,
Texas, March 2011–March 2012
By Larry Allain
Abstract
A floristics inventory was conducted to identify and
photograph the vascular plants occurring at Caddo Lake
National Wildlife Refuge (NWR), Texas, from March 2011
to March 2012 by the U.S. Geological Survey in cooperation
with the U.S. Fish and Wildlife Service. This research
resulted in the identification of 511 taxa of vascular plants
representing 111 families and 317 genera. Despite the degree
of development of the refuge at the time it was transferred to
the U.S. Fish and Wildlife Service, plant diversity was high.
Of the 511 species identified in this study, 346 species are new
records for Harrison County, and 3 species are new discoveries
for Texas. Caddo Lake NWR is primarily forested with 55 tree
species and 35 shrub species identified in this study. Of the
species identified, 289 are associated with wetlands having
a wetland classification of facultative or wetter, possibly
reflecting the proximity of Caddo Lake to the refuge and the
three streams that intersect the refuge. Sixty-two of the species
found on the refuge are introduced. Chinese tallow tree
(Triadica sebifera) is one of the more common invasive tree
species on the refuge and is actively controlled by refuge staff.
Chinese privet (Ligustrum sinense), sacred bamboo (Nandina
domestica), and King’s Ranch bluestem (Bothriochloa
ischaemum var. songarica) are present on the refuge and
have the potential to become invasive. More than 10,000
photographs were taken of the plants found on the refuge in an
effort to document general appearance and capture diagnostic
characters of each plant species. Photographs were also taken
of many of the animals and landscapes encountered during the
project. Select images of each of the plants and animals are
included in the collection of more than 1,600 photographs (all
photographs by Larry Allain).
Introduction
The National Wildlife Refuge System was established to
manage lands and waters in the United States for conservation
and restoration of fish, wildlife, and plant resources. There
are 560 national wildlife refuges in all, covering 61 million
hectares nationwide (U.S. Fish and Wildlife Service, 2013).
Individual refuges are unique and established for a variety
of purposes including the protection of endangered species;
the preservation of habitat for plants and animals threatened
by development or overutilization; the creation of habitat
connections and corridors within landscapes for migratory
animals; use as a recreational destination for hunting,
fishing, wildlife observation, and photography; facilitating
environmental education and interpretation; and restoring
lands and waters that have been damaged by past use. Most
national wildlife refuges have become general refuges for
every kind of wildlife that can appropriately be sheltered
in that environment. Maintaining and improving habitat
quality require that the biological integrity, diversity, and
environmental health of refuge resources be conserved.
To achieve these goals, each refuge is required by the
National Wildlife Refuge System Administration Act of
1997 to develop a 15-year comprehensive conservation plan.
Implementation of these plans requires the use of adaptive
management that relies on surveys, inventory and monitoring
of resources, management practices, and experiments.
The information gained is then used to alter and refine
management practices. A critical component of this process
includes the development of a comprehensive list of the
vascular plant species that occur on a refuge. Management
goals are affected when endangered species are identified.
Managing and restoring habitat require knowledge of existing
plant communities and the species they contain. Monitoring
invasive plant populations is necessary for their control or
eradication, and controlling new invasive plant problems is
most efficient when they are detected early in the invasion
cycle. Plant monitoring is performed by refuge personnel,
partners, and cooperators as budgets allow and is greatly
facilitated by a comprehensive plant list.
In addition to a plant list, refuge personnel often seek
plant information that would assist them in meeting their
management goals. Useful plant information might include
wildlife use, wetland affinity, and key characters that allow
differentiating species in the field. These data can be compiled
from existing publications.
2 A Comprehensive List and Photographic Collection of the Vascular Flora of Caddo Lake National Wildlife Refuge, Texas
From March 2011 to March 2012, the U.S. Geological
Survey in cooperation with the U.S. Fish and Wildlife Service
collected, identified, and photographed the vascular plants
occurring at Caddo Lake National Wildlife Refuge (NWR),
Texas. The goal of this project was to identify all vascular
plant species occurring at Caddo Lake NWR and to take
original photographs of each species while synthesizing
information on field identification traits and wildlife use.
Description of Study Area
Caddo Lake NWR is located in Harrison County, Tex.,
on lands transferred in October 2000 from the Department
of Defense, formerly the Longhorn Army Ammunition Plant
(fig. 1). The refuge was established on the less contaminated
portions of the retired munitions facility for the purpose of
converting the site to habitat for birds, fish, and other wildlife.
The 3,440-hectare refuge is divided by three drainages,
Goose Prairie Creek, Central Creek, and Harrison Bayou, that
flow north and east into Caddo Lake (U.S. Fish and Wildlife
Service, 2012). It is located in the pineywoods vegetation area
of northeast Texas (Hatch and others, 1990). A rolling ridge
and swale landscape, created by these drainages, provides a
variety of forest types and wetlands in this ancient drowned
river valley.
Caddo Lake, a 10,850-hectare cypress swamp, borders
the refuge on its eastern boundary (fig. 1). The soils are
primarily sandy loams with clay-loam occurring in the drain
bottoms. Forest types range from baldcypress (Taxodium
distichum var. distichum) in the lower parts of Harrison
Bayou to mixed pine-hardwoods on the slopes and pinedominated uplands. Shortleaf pine (Pinus echinata) savanna
is thought to have been the dominant plant community on the
highest elevations of the refuge, but these areas have largely
been reforested with loblolly pine (Pinus taeda). Refuge
management goals include restoring shortleaf pine savanna by
selective logging of loblolly pine and hardwoods.
Methods
Field trips were made monthly from March 2011 to
March 2012. Areas with variable hydrology, slope, elevation,
and history were identified from maps and interviews with
refuge personnel to select prospective sites for floristic
surveys. Selected areas were explored during each sampling
trip along with additional areas as time allowed. Individual
plants were photographed in the field, and plant specimens
were collected for laboratory inspection when identity
was uncertain. Voucher specimens are housed at the
U.S. Geological Survey National Wetlands Research Center
Herbarium in Lafayette, Louisiana. Plant identifications
were validated by using Correll and Johnston (1979), Flora
of North America Editorial Committee (1993+), and various
other manuals. Whether or not a species had been recorded
for Harrison County, Tex., was based on collection location
maps in the U.S. Department of Agriculture (USDA) PLANTS
database (http://plants.usda.gov/). Plant morphological
characters found to be diagnostic in field identification were
photographed for illustration purposes (fig. 2). Images were
organized and labeled by species scientific names based on the
Integrated Taxonomic Information System (http://www.itis.
gov/). Animals were photographed when encountered. Animal
images were cataloged by scientific name when known
and by common name when not. Insect identification was
accomplished by using Arnett (1993) and BugGuide (2012).
Results
In the course of this study, 792 plant specimens were
collected, identified, and labeled. More than 10,000 plant
photographs and 622 animal photographs were taken at the
refuge. The photograph collection in this report includes more
than 1,600 select plant, animal, and landscape images (all
photographs by Larry Allain).
This floristic inventory resulted in the identification of
511 taxa of vascular plants representing 111 families and
317 genera (table 1 at end of report). Phylogenetic families
representing the greatest species count or diversity were the
Asteraceae with 68, Poaceae with 62, Fabaceae with 43,
Cyperaceae with 30, Rosaceae with 16, Rubiaceae with 14,
Euphorbiaceae with 12, Lamiaceae with 12, Onagraceae
with 12, Apiaceae with 10, and Scrophulariaceae with
9 species. The genera with the most species were Carex
with 13, Juncus with 9, Quercus with 8, Ludwigia with 7,
Paspalum with 7, and Polygonum with 6 species.
Results 3
94°00'
MARION
COUNTY
2198
Goose
Prairie
Creek
Caddo Lake
Central
Creek
CADDO LAKE
NATIONAL WILDLIFE
REFUGE
Study area
Gu
lf
of
M
ex
ico
TEXAS
CADDO
PARISH
LOUISIANA
HARRISON
COUNTY
TEXAS
43
Harrison Bayou
32°30'
Base modified from U.S. Geological Survey
1:24,000 quadrangle digital data
Universal Transverse Mercator, zone 14
North American Datum of 1983
EXPLANATION
Caddo Lake National
Wildlife Refuge
Auto Route
Figure 1. Location of Caddo Lake National Wildlife Refuge, Texas.
0
0
5 MILES
5 KILOMETERS
4 A Comprehensive List and Photographic Collection of the Vascular Flora of Caddo Lake National Wildlife Refuge, Texas
Figure 2. Chambered pith of black walnut (Juglans nigra), an example of diagnostic plant characters photographed during this project
at Caddo Lake National Wildlife Refuge, Texas. Compound leaves of this tree are similar to leaves of hickories (Carya spp.), which can
be distinguished by having solid pith in their twigs.
Results 5
Of the 511 species identified in this study, 346 are
new records for Harrison County. According to the USDA
PLANTS database, three species, peelbark St. Johnswort
(Hypericum fasciculatum), changing forget-me-not (Myosotis
discolor), and pond cypress (Taxodium distichum var.
imbricarium) (fig. 3), are new to Texas. One species, Scleria
ciliata var. ciliate, is listed for Texas by Hatch and others
(1990) and one species, Pyrus calleryana, by Correll and
Johnston (1979), but no locations are listed in the USDA
PLANTS database for these two species.
Most of Caddo Lake NWR is forested with 56 tree
species and 33 shrub species identified in this study. Forest
types vary from pine forests on ridge tops to baldcypress
swamp flooded forests in creek bottoms and within the
frequently flooded sites near Caddo Lake. Pine-hardwood
forest dominates on slopes and much of the upland and
well-drained areas of Caddo Lake NWR (fig. 4). In pinehardwood forest, loblolly and shortleaf pine occur in
association with such hardwood species as southern red oak
(Quercus falcata), post oak (Quercus stellata), sweetgum
(Liquidambar styraciflua), water oak (Quercus nigra), willow
oak (Quercus phellos), white oak (Quercus alba), sugarberry
(Celtis laevigata), blackgum (Nyssa sylvatica), and winged
elm (Ulmus alata). Common understory shrub species in
pine-hardwood forest include hawthorns (Crataegus sp.),
American holly (Ilex opaca), waxmyrtle (Morella cerifera),
farkleberry (Vaccinium arboreum), red buckeye (Aesculus
pavia), flowering dogwood (Cornus florida), eastern redbud
(Cercis canadensis), sassafras (Sassafras albidum), southern
A
sugar maple (Acer barbatum), and American beautyberry
(Callicarpa americana). Those species most common
in ground cover vegetation are sedges (Carex spp. and
Cyperus spp.), tick trefoil (Desmodium spp.), elephantsfoot
(Elephantopus spp.), woodoats (Chasmanthium spp.), and
panicums (Panicum spp. and Dichanthelium spp.). On the
forest edge, vines predominate, with peppervine (Ampelopsis
arborea), Virginia creeper (Parthenocissus quinquefolia),
Alabama supplejack (Berchemia scandens), greenbriars
(Smilax spp.), poison ivy (Toxicodendron radicans), and
grapes (Vitis spp.) being most common.
Tree species that occurred in low areas along creek
drainages and in frequently flooded parts of the refuge include
baldcypress, overcup oak (Quercus lyrata), water oak, willow
oak, green ash (Fraxinus pennsylvanica), bitter pecan (Carya
aquatica), and sweetgum (fig. 5). Common smaller trees and
shrubs include planertree (Planera aquatica), swamp privet
(Forestiera acuminata), water locust (Gleditsia aquatic),
buttonbush (Cephalanthus occidentalis), and possumhaw (Ilex
decidua). Herbaceous ground cover in wet areas included
mostly sedges, rushes (Juncus spp.), smartweeds (Persicaria
spp.), heliotrope (Heliotropium indicum), camphorweeds
(Pluchea spp.), lizard’s tail (Saururus cernuus), primrosewillows (Ludwigia spp.), and rosemallow (Hibiscus
moscheutos ssp. lasiocarpos). Vines most common in these
areas were climbing hempvine (Mikania scandens), buckwheat
vine (Brunnichia ovata), and climbing dogbane (Thyrsanthella
difformis).
B
Figure 3. The differences in leaf form of two varieties of Taxodium distichum occurring on Caddo Lake National Wildlife Refuge, Texas.
A, Taxodium distichum var. imbricarium, a new taxon for Texas, has scale-like leaflets on upward oriented leaves. B, Taxodium distichum
var. distichum has descending leaves and linear leaflets.
6 A Comprehensive List and Photographic Collection of the Vascular Flora of Caddo Lake National Wildlife Refuge, Texas
Figure 4. Pine-hardwood forest predominant on slopes and other well-drained sites in Caddo Lake National Wildlife Refuge, Texas.
Figure 5. Bottomland hardwoods dominated by baldcypress (Taxodium distichum var. distichum) along drainages and in frequently
flooded parts of Caddo Lake National Wildlife Refuge, Texas.
Results 7
Many of the vascular plants that occur in shortleaf
pine understory were present on the refuge, but most were
uncommon. Grasses, growing mostly on roadsides and that
are associated with savanna understory, include splitbeard
bluestem (Andropogon ternarius), woodoats, little bluestem
(Schizachyrium scoparium), switchgrass (Panicum virgatum),
prairie panicgrass (Panicum brachyanthum), brownseed
paspalum (Paspalum plicatulum), eastern gamagrass
(Tripsacum dactyloides), purpletop (Tridens flavus),
arrowfeather three-awn (Aristida purpurascens), and rosette
grasses (Dichanthelium spp.). Several conservative species
usually confined to undisturbed shortleaf pine understory
and prairies were identified, including nodding lady’s tresses
(Spiranthes cernua), dwarf sundew (Drosera brevifolia), and
pinkscale blazing star (Liatris elegans). Other wildflowers of
pine savanna occurred in small populations such as sidebeak
pencilflower (Stylosanthes biflora), diamond flowers (Stenaria
nigricans), multibloom hoarypea (Tephrosia onobrychoides),
roughleaf coneflower (Rudbeckia grandiflora), hairyflower
spiderwort (Tradescantia hirsutiflora), Carolina anemone
(Anemone caroliniana), groovestem Indian plantain
(Arnoglossum plantagineum), and butterfly milkweed
(Asclepias tuberosa).
Wetland indicator status (Lichvar, 2013) of the taxa
identified in this study indicated that most of the species are
wetland plants, possibly reflecting the proximity of Caddo
Lake and the three streams that intersect the refuge. While
222 species were categorized as upland or facultative upland
plants, 289 are associated with wetlands with 122 facultative,
78 facultative wet, and 82 obligate wetland species.
Of the 511 taxa identified in this study, 62 were
introduced (table 2 at end of report). Most nonnative species
have become naturalized and make up a small part of the
flora, although several are invasive and pose a risk to native
vegetation and wildlife habitat quality. Chinese tallow tree
(Triadica sebifera) is highly invasive and is a management
priority for refuge staff (figs. 6 and 7). Other nonnative trees
including flowering pear (Pyrus calleryana), silk tree (Albizia
julibrissin), and Chinaberry tree (Melia azedarach) are
Figure 6. Chinese tallow tree (Triadica sebifera), an invasive
nonnative species that is currently controlled by refuge
management at Caddo Lake National Wildlife Refuge, Texas.
Pictured here in the fall of the year is a branch bearing white
seeds and leaves beginning to turn colors.
present but do not appear to pose a risk of becoming invasive.
Chinese privet (Ligustrum sinense) is present and has not
yet become invasive at Caddo Lake NWR. Elsewhere in east
Texas forests, Chinese privet has become a nuisance invader
in forest understory. Another understory shrub with a history
of invasion, sacred bamboo (Nandina domestica), was rare on
the refuge but should be part of an active eradication program
(fig. 8). While numerous nonnative forbs and grasses bloom
on the roadsides of Caddo Lake NWR, one grass species
is problematic. King’s Ranch bluestem or KR bluestem
(Bothriochloa ischaemum var. songarica) has spread eastward
and northward from south Texas along roadsides in the past
15–20 years colonizing disturbed grasslands, roadsides, and
old agricultural fields. Mowing may speed its spread, and it
has the potential to exclude other species. Without a control
strategy, the diverse and colorful variety of wildflowers lining
the roads at Caddo Lake NWR may become a monoculture of
KR bluestem.
8 A Comprehensive List and Photographic Collection of the Vascular Flora of Caddo Lake National Wildlife Refuge, Texas
Figure 7. Staff of Caddo Lake National Wildlife Refuge, Texas, using herbicide to treat small Chinese tallow trees (Triadica sebifera)
before these nonnative, highly invasive trees can bear seeds and colonize additional area.
Discussion 9
Figure 8. An invasive understory shrub, sacred bamboo
(Nandina domestica), that was collected on a small outholding of
Caddo Lake National Wildlife Refuge, Texas, north of Texas Farm
to Market Road 2198 (FM 2198).
Giant salvinia (Salvinia molesta), considered one of
the world’s worst aquatic pests (Oliver, 1993), has become
a major problem in Caddo Lake (fig. 9). A native of Brazil
(Everitt and others, 2007), giant salvinia impedes navigation
and reduces sunlight and oxygen, killing beneficial plants,
insects, and fish. It can clog agricultural irrigation ditches
Figure 9. Giant salvinia (Salvinia molesta), considered one of the
world’s worst aquatic pests. It has become a major problem on
Caddo Lake at Caddo Lake National Wildlife Refuge, Texas.
and impair electrical generation (Holm and others, 1977).
Experimental research is being conducted by the Caddo Lake
Institute in cooperation with Caddo Lake NWR to investigate
the use of a beetle (Cyrtobagous salviniae) for biological
control of this aggressive weed.
In addition to wild species, planted species were also
collected and photographed during this project. A live oak
tree (Quercus virginiana) apparently planted as a landscape
specimen near the refuge office was the only individual of that
species occurring on the refuge. Indian paintbrush (Castilleja
indivisa) and firewheel (Gaillardia pulchella) growing on the
roadside at the entrance of the refuge are commonly planted
on roadsides in Texas and were not found elsewhere on the
refuge. A combination of plant species including Illinois
bundleflower (Desmanthus illinoensis), plains snakecotton
(Froelichia floridana), and Maximilian sunflower (Helianthus
maximiliani) dominated the road median in front of the
refuge office and was reported to be the results of a grassland
planting conducted by Texas Parks and Wildlife Department
(Jason Roesner, assistant refuge manager, oral commun.,
2011). Plant species thought to have been planted are labeled
in table 1.
Discussion
Despite the developed nature of the Longhorn Army
Ammunition Plant at the time it was transferred to the U.S.
Fish and Wildlife Service, considerable plant diversity can be
found at the refuge. Forest types range from pine-hardwood on
ridges to cypress-dominated bottomland hardwoods along the
three drainages and the lake margin. Diverse communities of
herbaceous plant species on roadsides and in forest clearings
include remnant species common in predevelopment plant
communities, as well as ruderal species.
In the wettest areas of the refuge, plants such as
smartweeds (Persicaria spp.) and primrose willows (Ludwigia
spp.) provide food for overwintering waterfowl (table 3 at
end of report). Diverse grassy areas provide quality habitat
for grassland species. Occasional deer, wild turkeys, northern
bobwhite (Colinus virginianus), eastern cottontail (Sylvilagus
floridanus), coyote (Canis spp.), gray (Sciurus carolinensis)
and fox (Sciurus niger) squirrels, and numerous other animals
can be glimpsed along the Auto Route (a 6-mile-long auto tour
through a small portion of the refuge; fig. 1). At the western
end of their range at Caddo Lake NWR, three-toed box turtles
(Terrapene carolina triunguis) can sometimes be seen in open
forest or on roadsides, especially during their March and April
breeding season (fig. 10).
10 A Comprehensive List and Photographic Collection of the Vascular Flora of Caddo Lake National Wildlife Refuge, Texas
Figure 10. A three-toed box turtle (Terrapene carolina triunguis), so named because of the number of toes on the back feet, at Caddo
Lake National Wildlife Refuge, Texas. Their range extends from east Texas to the Florida Panhandle.
Numerous species of birds reside year-round or migrate
through the refuge during spring and fall including eastern
bluebird (Sialia sialis), American woodcock (Scolopax
minor), yellow-breasted chat (Icteria virens), rufous-sided
towhee (Pipilo erythrophthalmus), and white-throated sparrow
(Zonotrichia albicollis). Butterflies and numerous other insects
can be seen along the roadsides in spring and fall (fig. 11).
Widening of grassy areas along the refuge’s Auto Route and
other interior roads could provide additional habitat for native
pollinators and other grassland insect species.
Roadsides within the refuge provide a colorful show of
wildflowers. Trees, with their leaf, flower, and seed displays,
create a vivid natural experience for visitors. Many of the
species listed as constituents of shortleaf pine understory
are present on the refuge and could be restored as part of
the refuge’s goal of restoring shortleaf pine savanna. Such a
restoration strategy would enhance the value of these forests
for wildlife, as well as create a more rewarding experience for
refuge visitors.
Figure 11. American lady butterfly (Vanessa virginiensis)
nectering on the flowers of groovestem Indian plantain
(Arnoglossum plantagineum) on a roadside along the Auto Route
in Caddo Lake National Wildlife Refuge, Texas. A wide variety of
butterflies and skippers occur on the refuge.
References Cited 11
Summary
From March 2011 to March 2012, vascular plants were
collected and photographed at Caddo Lake National Wildlife
Refuge (NWR), Texas, to produce a floristic inventory. The
goal of this project was to create both a comprehensive list of
the refuge’s vascular flora and a photographic record of each
plant species. This plant inventory resulted in the identification
of 511 taxa of vascular plants representing 111 families
and 317 genera. Of the species identified in this study, 346
are new records for Harrison County. Caddo Lake NWR is
primarily forested with 56 tree species and 33 shrub species
identified in this study. Of the plant species identified, 289
are associated with wetlands having a wetland classification
of facultative or wetter. Sixty-two of the species found on the
refuge are introduced, including the invasive Chinese tallow
tree (Triadica sebifera), Chinese privet (Ligustrum sinense),
sacred bamboo (Nandina domestica), and King’s Ranch
bluestem (Bothriochloa ischaemum var. songarica). More than
10,000 photographs were taken of plants found on the refuge
in an effort to document general appearance, as well as the
diagnostic characters of each plant species. Photographs were
also taken of wildlife encountered during the collective field
trips. Of the photographs taken, more than 1,600 select digital
images of plants, animals, and landscapes are included in the
photograph collection (all photographs by Larry Allain).
Acknowledgments
Correll, D.S., and Johnston, M.C., 1979, Manual of the
vascular plants of Texas: The University of Texas at Dallas,
1,880 p.
Everitt, J.H., Lonard, R.L., and Little, C.R., 2007, Weeds in
south Texas and northern Mexico: Lubbock, Texas Tech
University Press, 240 p.
Flora of North America Editorial Committee, eds., 1993+,
Flora of North America—North of Mexico: New York,
Oxford University Press, 16+ v.
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