Know Your Natives – American Hazelnut

American Hazelnut

American Hazelnut (Corylus americana) is a medium to large spreading shrub that produces edible nuts in the fall.

The nuts ripen in September and October and are a favorite of small game and birds. As fall progresses male catkins are produced. In mid to late winter the catkins fully expand and shed their pollen. A large, leafless shrub in February with fully grown catkins is a sight!

It is found over much of the central and eastern United States north of the Gulf Coast. Arkansas is at the southwestern edge of this species’ range.

American Hazelnut - Corylus americana

Next season’s male catkins form as fall progresses

American Hazelnut - Corylus americana

The maturing nuts are enclosed in a protective structure known as an involucre

Article and photographs by ANPS member Eric Hunt

Terms of Use

Posted in Know Your Natives, Native Plants, Trees | Tagged , ,

Ash Tree Threat Invades Arkansas

Arkansas joins the growing list of states affected by the Emerald Ash Borer (Agrilus planipennis), or EAB for short, an invasive Asian beetle devastating North American ash trees.

Adult EAB.  Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org.

Adult EAB. Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org.

The beetle was first discovered on the continent in Michigan in 2002, although it apparently arrived a few years earlier, possibly introduced as larvae in ash wood packing material.  In a little over a decade and a half or so it has spread throughout the Great Lakes region to well into the Northeast and Midwest, killing tens of millions of ash trees, and now, sadly, is advancing into the South.

: Ash trees dead or dying from EAB infestation in Virginia.  Christopher Asaro, Virginia Department of Forestry, Bugwood.org.

Ash trees dead or dying from EAB infestation in Virginia. Christopher Asaro, Virginia Department of Forestry, Bugwood.org.

After discovery of EAB in southeastern Missouri in 2008, the Arkansas State Plant Board and the United States Department of Agriculture began surveying in 2009 for EAB in Arkansas with the use of lure-baited insect traps and by inspecting ash trees for signs of infestation.  EAB was detected this summer in traps in southwestern Arkansas and by subsequent field inspections.  It is now confirmed from six counties: Clark, Columbia, Dallas, Hot Spring, Nevada, and Ouachita.  Given the extent of the infestation, it has likely been in the area for a couple of years.

EAB larvae and damage to an ash tree in Ouachita County, AR.  Arkansas State Plant Board.

EAB larvae and damage to an ash tree in Ouachita County, AR.  Arkansas State Plant Board.

The adults of EAB are small (about 1/3 to 1/2 inch) and metallic green.  The upper side of their abdomens (exposed when the wings are extended) is coppery- or purplish-red, a distinctive character of this species.

adult_David Cappaert_Michigan State University_Bugwood_org

Adult EAB, with distinctive purplish-red upper abdomen exposed. David Cappaert, Michigan State University, Bugwood.org.

The adults are present and breeding during the summer, with females depositing their eggs in bark crevices of living ash trees.  However, it’s the larvae, linear and whitish with bell-shaped segments, which do the damage, boring extensive, meandering tunnels under the bark while feeding on the vascular tissues, eventually destroying the tree’s vascular transport system, essentially girdling it.

Larva of EAB.  Note bell-shaped segments.  David Cappaert, Michigan State University, Bugwood.org.

Larva of EAB. Note bell-shaped segments. David Cappaert, Michigan State University, Bugwood.org.

Tunnels (galleries) bored through vascular layer of an ash tree by EAB larvae.  Troy Kimoto, Canadian Food Inspection Agency, Bugwood.org.

Tunnels (galleries) bored through vascular layer of an ash tree by EAB larvae. Troy Kimoto, Canadian Food Inspection Agency, Bugwood.org.

Once heavily infested, the tree can no longer transport water or nutrients from the roots to the leaves or sugars produced during photosynthesis in the leaves to the rest of the plant.  Branch dieback and sparse foliage are often early symptoms of an infestation, progressing to top-killed trees with prolific branching from the base of the trunks or roots, peeling and splitting of the bark, and eventually death (often within three to five years of initial infestation).

Ash tree infested with EAB.  Note top-killed tree and prolific, basal sprouting.  Daniel Herms, The Ohio State University, Bugwood.org.

Ash tree infested with EAB. Note top-kill and prolific, basal sprouting. Daniel Herms, The Ohio State University, Bugwood.org.

After the larvae pupate, the adults emerge in the spring through characteristic D-shaped holes bored through the bark.

exit hole_Pennsylvania Department of Conservation and Natural Resources_Forestry Archive_Bugwood_org

Characteristic D-shaped exit hole through which adult EAB emerges. Pennsylvania Department of Conservation and Natural Resources, Forestry Archive, Bugwood.org.

All true ashes (members of the genus Fraxinus) are hosts and are detrimentally affected by the beetle.  In Asia, ash tree species which have co-evolved with EAB have developed a chemical resistance to the larvae, greatly inhibiting the number of larvae and the extent of damage they cause.  North American ash trees, however, have no natural resistance.  In Arkansas, we have at least five native ash species, two of which occur statewide: green ash (F. pennsylvanica) which is common in bottomlands and on river terraces, and white ash (Fraxinus americana) found in a wide range of habitats (some authorities recognize additional species segregated from white ash, such as F. biltmoreana and F. smallii).

geren ash bark_karen a rawlins_university of georgia_bugwood_org

Leaf and bark of green ash (Fraxinus pennsylvanica). Karen A. Rawlins, University of Georgia, Bugwood.org.

Fruit (samaras) of green ash (Fraxinus pennsylvanica).  Paul Wray, Iowa State University, Bugwood.org.

Fruit (samaras) of green ash (Fraxinus pennsylvanica). Paul Wray, Iowa State University, Bugwood.org.

The three remaining ashes are each regionally and more ecologically restricted: Carolina ash (F. caroliniana) of swamps and bottomland forests in the West Gulf Coastal Plain, pumpkin ash (F. profunda) of swamps and bottomland forests in the Mississippi Alluvial and eastern West Gulf Coastal Plains, and blue ash (F. quadrangulata) of primarily calcareous uplands in the Ozark Mountains and southwestern Arkansas.  Although ash trees make up only about 2.5% of the total forest composition of the state (a slightly higher percentage in the Mississippi Alluvial Plain), their ecological, economic, and aesthetic values are significant.  Other native (i.e., fringe-tree [Chionanthus virginicus] and swamp privet [Forestiera acuminata]), and cultivated and introduced (e.g., forsythias [Forsythia spp.], lilac [Syringa vulgaris], privets [Ligustrum spp.]) members of the olive family (Oleaceae), to which the ashes belong, do not appear to be affected in Arkansas at this point.

Systemic insecticides (transported within the tree’s vascular system) can be used to protect specimen ash trees, in yards or urban landscapes, for example, but treatment must begin before an infestation is well underway and must be repeated multiple times over numerous years for continued protection (perhaps indefinitely, which could be ultimately rather costly).  Once symptoms are noted (especially more than 50% of canopy dieback), it is likely too late for the tree to be saved, as considerable damage to the tree’s vascular system has already occurred.  Unfortunately, protection of trees in forested habitats is unfeasible at this time.

Although EAB is believed to spread relatively slowly on its own (on the order of a few miles per year), its spread has been greatly accelerated by movement of infested firewood, nursery stock, timber, and other wood products, often resulting in leaps of tens to hundreds of miles.  One or more of these was the likely cause (and probable additional dispersal) of the Arkansas infestation.  Last month, the Arkansas Sate Plant Board implemented an emergency quarantine to regulate movement of items that pose a significant threat of spreading EAB further.

Emergency EAB Quarantine area in Arkansas, including the six infested counties and 19 buffer counties.

Emergency EAB Quarantine area in Arkansas, including the six infested counties and 19 buffer counties.

Unless a compliance agreement can be obtained through the Arkansas State Plant Board, items restricted from movement from within to outside the quarantine area include firewood (of all hardwood species, since it is sometimes difficult to distinguish species of cut logs), ash nursery stock, green ash lumber with bark attached, and other ash material (living or dead) greater than one inch in size.  Quarantined items can move freely within the quarantined area.  This emergency quarantine will be effective for 120 days, during which time the Arkansas State Plant Board will take steps to establish a permanent quarantine rule, a process that will require a public comment period.

Of particular concern among the regulated items is firewood, as monitoring of firewood movement is extremely difficult.  Campers, hunters, and others recreating in Arkansas are being implored to use wood for campfires collected only from the local area and not to transport firewood more than 25 miles from its origin.  If firewood is moved beyond such limits by accident or prior to being aware of the regulations, it should be burned in its entirety as soon as possible and as safely as possible.  Such firewood should not be left unburned for future campers or further transported.

If you suspect an EAB infestation or note ash trees exhibiting unexplained damage or mortality, especially outside of the six known infested counties, contact the Arkansas State Plant Board (501-225-1598), your local Cooperative Extension Office, or your local forester.

And, if you’ve ever had any tree-hugging inclinations, perhaps you might want to hug your favorite ash tree(s) while you still can.  You will not be judged…there’s no shame.  I’ve already a hugged a few.

Article by ANPS member and Arkansas Natural Heritage Commission botanist Brent Baker.

Terms of Use

Posted in Trees | Tagged , , ,

Know Your Natives – Yellow False Foxgloves

Comb-Leaf Yellow False Foxglove and Smooth Yellow False Foxglove

Comb-leaf yellow false foxglove (Aureolaria pectinata) and smooth yellow false foxglove (Aureolaria flava) are hemiparasitic (obtain some nutrients from other plants) plants, but do also have chlorophyll and perform photosynthesis.  These yellow false foxgloves attach to oak tree roots via haustoria (modified roots that penetrate the host’s tissues).  They are sometimes also called “oak leaches” for this reason.  Previously placed in the traditional Scrophulariaceae (Figwort) Family, the yellow false foxgloves and other hemiparasitic species have since been transferred to the Orobanchaceae (Broom-rape) Family.  The genus name “Aureolaria” in Latin refers to the golden-yellow flowers of these species.

Plant color is medium green for yellow false foxgloves, and leaves and flowering branches are opposite.  Leaves, flowering branches and flowers grow from leaf axils.  Trumpet-shaped and canary-yellow flowers, occurring in late summer to early fall, are solitary on short pedicels.  The corollas have five rounded spreading lobes (two on top and three on bottom) that fuse to form a trumpet-shaped tube.  Four overhanging stamens are fused to the bottom of the tube.  A slender style from the superior ovary protrudes slightly beyond the grouped stamens.  Ovoid seed capsules split when mature and dry.

Yellow false foxgloves are pollinated by bumble bees and hummingbirds.  They are also larval host plants for the Baltimore checkerspot butterfly.

Comb-Leaf Yellow False Foxglove

Comb-leaf yellow false foxglove, an annual, occurs in the US from eastern Texas and Oklahoma to Missouri and eastward to the Atlantic Coast.  In Arkansas, it is mainly found in highlands of the Ozark and Ouachita Mountains (including the mountains and ridges of the Arkansas Valley).  Comb-leaf yellow false foxglove grows in sandy to rocky, open woodlands and glades in thin, dry, acidic soils.  Young plants have a rosette of basal leaves which are elliptic to lance-like and entire (no indentions).  Mature plants, up to three feet tall, may consist of a single main stem with minimal branching or a single stem with many branches. The plant is densely covered with glandular hairs and feels sticky to the touch.  Leaves, generally 1.5” long and 0.75” wide with three to seven pinnate (feather-like) primary lobes, are deeply cut or comb-like (thus “pectinata” in the Latin name).  Leaves are generally sessile except that lower leaves can be somewhat petiolate.

Photo 1

Photo 1:  Spring growth of comb-leaf yellow false foxglove (an annual) showing simple basal leaves and pinnate leaves higher up-stem.

Photo 2

Photo 2:  A single stemmed comb-leaf yellow false foxglove.  Note dense hairs and reddish tip of flower buds.

Comb-leaf yellow false foxglove flowers August to September with blooms up to 1.5″ long and 0.75” wide.  The calyx, formed by five pinnate sepals, is densely hairy as is the outside of flower buds and flowers.  The ends of flower buds may be reddish and reddish streaks may occur along the lower-inside of the floral tube.

Photo 3

Photo 3:  Stamens and style allow ample space for a bubble bee or hummingbird.  Small bees, as shown, likely do not facilitate pollination.

Smooth Yellow False Foxglove

Smooth yellow false foxglove, a perennial, occurs in the US from Texas to Wisconsin and eastward to the Atlantic Coast.  In Arkansas, it occurs in a rather odd distribution including much of the Ozarks, eastern Ouachita Mountains, and southeastern part of the state.  It is curiously sparse in the western Ouachitas, and mostly absent from the western Gulf Coastal Plain and much of the Mississippi Alluvial Plain.  Smooth yellow false foxglove is generally found in dry, open upland oak or pine-oak woodlands (savannas).  It is an upright to sprawling plant to four feet tall with smooth, hairless stems.  Lower flowering branches may be 1.5 feet long with subsequent branches decreasing in length.  Lower leaves, three to four inches long, are deeply lobed with lobes being narrow and decreasing in length toward the tip.  Width of central section of leaf blade and width of lobes are similar.  Minor secondary lobes occur.  Leaves on flowering branches, about 1.5” long, are willow-like.  Leaves and lobes are slightly folded along their central veins.

Photo 4

Photo 4:  Spring growth of smooth yellow false foxglove (a perennial).  Dry stalks from last year’s growth still present.

Photo 5

Photo 5:  Multi-stemmed smooth yellow false foxglove grows quickly and may reach four feet tall.

Flowers, up to two inches long and 1.5 inches wide, are in a raceme or, near the top, directly from the main stem.  The short, cup-like calyx is rimmed by five short, pointed sepals.

Photo 6

Photo 6:  A flowering smooth yellow false foxglove presents a rather loose, disorganized appearance.

Photo 7

Photo 7:  Leaf comparison of Aureolaria pectinata (comb-leaf yellow false foxglove) and Aureolaria flava (smooth yellow false foxglove)

Footnotes – additional yellow false foxglove species of note:

Large-flower yellow false foxglove (Aureolaria grandiflora) is the only other species of the group that occurs in Arkansas.  It is perennial and somewhat resembles smooth yellow false foxglove in habit, but is densely short-hairy (but not glandular or sticky hairy like comb-leaf yellow false foxglove).  The main stem leaves often tend to be less deeply lobed and the flowering stem leaves shorter and broader than smooth yellow false foxglove.  Large-flower yellow false foxglove, also has a rather odd distribution in Arkansas, occurring in the western Ozarks, western Ouachitas, Gulf Coastal Plain and on Crowley’s Ridge.  Although it occurs in similar habitats to smooth yellow false foxglove, large-flower yellow false foxglove is generally absent from the central part of the other’s range in the state.  However, their ranges do overlap, especially from the northwestern corner of the state, through central Arkansas, into the southeastern corner, and plants of both species can sometimes be found growing together in this region.

Fern-leaf yellow false foxglove (Aureolaria pedicularia), an annual, is very similar to comb-leaf yellow false foxglove.  In fact, they are sometimes treated as variants of a single species.  Whereas comb-leaf yellow false foxglove is distributed throughout the Southeastern U.S., fern-leaf yellow false foxglove is more northern in distribution, generally restricted to the Great Lakes and East Coast/Appalachian regions.  Fern-leaf yellow false foxglove, in this stricter sense, is not known from or expected to be found in Arkansas, but references to Aureolaria pedicularia in the state may be found in some literature reports, owing to the two being combined under this name at times.

Article and photographs by ANPS member Sid Vogelpohl

Terms of Use

 

Posted in Know Your Natives | Tagged ,