arrow arum (Peltandra virginica)
green water arum
green arrow arum
Alocasia virginica (L.) Raf.
Arum virginicum L.
Arum walteri Elliott
Caladium undulatum Steud.
Caladium virginicum (L.) Hook.
Calla virginica (L.) Michx.
Lecontia virginica (L.) Torr.
Peltandra angustifolia Raf.
Peltandra canadensis Raf.
Peltandra hastata Raf.
Peltandra heterophylla Raf.
Peltandra latifolia Raf.
Peltandra luteospadix Fernald
Peltandra tharpii F. A. Barkley
Peltandra undulata Raf.
Peltandra undulata Schott
Peltandra virginica forma angustifolia (Raf.) S.F.Blake
Peltandra virginica forma brachyota S.F.Blake
Peltandra virginica forma hastifolia S.F.Blake
Peltandra virginica forma heterophylla (Raf.) S.F.Blake
Peltandra virginica forma latifolia (Raf.) S.F.Blake
Peltandra virginica forma rotundata S.F.Blake
Peltandra virginica subsp. luteospadix (Fernald) W.H.Blackw. & K.P.
Peltandra virginica var. angustifolia (Raf.) Tidestr.
Peltandra virginica var. heterophylla (Raf.) Tidestr.
Peltandra walteri (Elliott) Raf.
Rensselaeria virginica (L.) L.C.Beck
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name of arrow arum is
Peltandra virginica (L.) Schott. Leaf shape is highly variable in Peltandra
virginica, and different forms have been recognized taxonomically, both
at the specific and infraspecific levels. Because leaf shape varies within
populations and even within an individual clump of plants, Peltandra
virginica is treated here as a single taxon.
The leaves of arrow arum superficially resemble those of another wetland plant, Sagittaria latifolia (common arrowhead). While the leaves of arrow
arum have pinnate venation (e.g., a central vein with lateral veins), the
leaves of common arrowhead have palmate venation (even though many
of these veins appear to be parallel). Common arrowhead also produces a
narrow raceme of showy white flowers with 3 petals, which has a very
different appearance from the inflorescence of arrow arum.
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: This perennial plant is an emergent aquatic that forms clumps of
basal leaves on stout petioles.
Leaves: The ascending basal leaves are 8-24" long and 4-10" across;
they are hastate to sagittate with pointed basal lobes, smooth along their
margins, pinnately veined, medium to dark green, and glabrous. The
stout petioles of the basal leaves are 12-30" long; they are light green and
glabrous. The leaves are deciduous in northern areas, but they are ever-
green in areas along the Gulf Coast.
Flowers: The tiny flowers are arranged along a cylindrical spadix that is
surrounded by a narrow spathe; this inflorescence is 4-8" long. The spathe
is light green and glabrous, tapering gradually at both ends; it has whitish
green wavy margins and remains open in the middle. The spadix is white,
cream, or pale yellow. Arrow arum is monoecious; fertile female flowers
are located at the bottom of the spadix, while male flowers are located
above. Sterile male flowers are located between fertile male flowers and
fertile female flowers. Each fertile male flower has 4-5 stamens, while
each fertile female flower has a single-celled ovary with a short style; the
flowers have neither petals nor sepals. The stout peduncle of the inflores-
cence is 8-18" long, light green, and glabrous. The blooming period occurs
from late spring to early summer for about 2-3 weeks.
Fruit/Seeds: Afterwards, the lower portion of the spadix develops an
ovoid cluster of berries, while rest of the spadix rots away. As the berries
become mature, the peduncle bends downward, inserting the berries into
the water. The tip of the spathe drills into the underlying muck, releasing
some of the berries. The released berries have the capacity to float on
water, thereby distributing the seeds into new areas. Each globoid berry
is about ½" across; the skin of the berry varies in color from green to
brown, while its interior contains clear mucilage and 1-3 chunky seeds.
Roots: The root system consists of stout vertical rootstalks and fleshy
fibrous roots; as the root mass expands, vegetative offsets are formed.
This plant often forms colonies of varying size.
REGENERATION PROCESS: The flowers of arrow arum are pol-
linated by a chloropid fly, Elachiptera formosa (Diptera: Chloropidae),
which uses the inflorescence as a mating site and a larval food source.
Eggs are deposited within the inflorescence, and the emerging larvae
feed on the rotting male portion of the spadix. The fruits are primarily
dispersed by water, although animals also play a role.
HABITAT TYPES: Arrow arum preference is for wetland habitats,
including shallow water areas bogs, swamps, freshwater to low-salinity
tidal marshes, and ditches, as well as along the edges of ponds, lakes, and
rivers, or wet spots in the forest. Habitats include swamps, shallow water
along ponds, bottoms of slow-moving shallow rivers, and ditches. Arrow
arum is typically found in shaded or partially shaded areas of wetlands,
rather than in open sunny areas.
SITE CHARACTERISTICS: Arrow arum prefers partial sun to light
shade, standing water up to 1' deep, and muck containing organic matter,
sand, or peat. This emergent requires unconsolidated silty or organic sites,
which are open, and saturated or inundated up to 1 foot. It will tolerate
pHs of 3.0 to 9.5, and salinity up to 2 ppt. Arrow arum grows from sea
level up to about 3,600 feet. This plant is bothered by very few disease
organisms and insect pests.
SEASONAL DEVELOPMENT: Flowering occurs from spring to
late summer, but can continue into the fall and winter in the extreme
southern areas of its range.
GENERAL DISRIBUTION: Populations of arrow arum are most com-
mon along the Atlantic Coastal Plain from southern Canada southward,
but its range appears to be actively expanding. Since 1978, the species
was reported as new to the floras of Iowa, Kansas, Minnesota, West Vir-
ginia, and Wisconsin, and introduced populations may persist in Oregon
and California. Fruits and seeds of arrow arum are a food for wildlife,
especially waterfowl, and their use by migratory birds is an important fac-
tor in the spread of this species.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: The unusual inflorescence produces
an odor that attracts flies. The primary pollinator of the flowers is the
Chloropid fly, Elachiptera formosa. This fly lays its eggs on specialized
tissues of the spadix, and cross-pollinates the flowers while wandering
from inflorescence to inflorescence. The adults feed on pollen. Other
visitors of the flowers include a Syrphid fly, Helophilus spp., and a fruit
fly, Drosophila subpalustris; the adults of these flies also feed on pollen.
Two semi-aquatic leaf beetles, Donacia tuberculata and Plateumaris
shoemakeri, feed on the foliage of arrow arum. The berries are eaten by
the wood duck, mallard, and king rail; these birds probably spread the
seeds into new areas. Thereis also some evidence that the snapping turtle
(Chelydra serpentina) and midwestern painted turtle (Chrysemys picta
marginata) use arrow arum as a food source. Mammalian herbivores
avoid consumption of this plant because of its toxicity: both the roots
and foliage contain crystals of calcium oxalate that can cause severe ir-
ritation of the gastrointestinal tract and kidney failure.
Expansive stands of arrow arum often develop in the marginal waters it
inhabits. The foliage and stems in these stands create a wave deflecting or
buffering barrier, while the root masses knit together and stabilize the
submerged sediments. The roots and shoots translocate methane from
the substrate. Arrow arum fruit is a preferred food of wood ducks, and is
also eaten by muskrats and rails. The foliage is seldom damaged, provid-
ing good cover to waterfowl, wading birds, insects, and aquatic mammals.
Arrow arum may have been an important food plant for eastern Native
Americans, especially in the mid-Atlantic coastal region from Pennsyl-
vania to Virginia, where the plants are now common and grow in large,
dense populations. Historical accounts mention use of the rhizomes as
well as the leaves, fruits, and seeds as food.
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