By Stephen Futch, Kenneth Jones and David Hall The emergent aquatic plants dis- minimizing potential for grove flood- cussed in this article are frequently found ing or elevated water tables that will in and around ditches, canals and ponds impact citrus root growth. in or near citrus groves. These emergent Additional articles on floating and aquatic weeds may need to be treated submersed aquatic weed species are with herbicides to maintain adequate planned for Citrus Industry magazine water flow in ditches and canals, thereby later this year.

Vic Ramey, ©2000, UF Vic Ramey, ©2002, UF Ann Murray, ©1999, UF ALLIGATOR WEED CATTAIL CUBAN BULRUSH, Alternanthera philoxeroides Typha spp. (Typha domingensis, BURHEAD SEDGE Leaves: opposite, with a rim between and T. latifolia) Oxycaryum cubense the bases, margins smooth, elliptical, 2 to 5 Leaves: straplike, spongy, upper surface concave, lower surface slightly rounded, tip of blade nearly flat; (syn. Scirpus cubensis) inches long, and one quarter to three-quar- Leaves: all near the base and often ters inch wide, lanced-shaped; tiny erect base of the blade can reach 2.5 inches wide, gradually narrowing upward longer than the stem hairs are found in leaf axils and rims Stem: slender triangular stolons, to Stem: round, hollow, often pinkish in Stem: extensive, fast-growing rhizomes Flowers: unisexual, brown, extremely small in size 2½ feet; upright shoots form along the color, roots at nodes, to 3 feet long forming a dense cigar-shaped spike that ranges from stolons white, in a solitary head on a Flowers: 6 inches to 1.7 feet long; the male section of the spike Flowers: one to 13, stalked, spheri- long stalk, non-sexual parts of flower papery includes the stamens and is located above the female cal clusters one-quarter to one-half inch Seeds: none produced in Florida; repro- section of the spike containing the pistils; the section in diameter, surrounded by two to six or duction is vegetatively by fragmentation with the male flowers is usually narrower than the more modified leaves Height: prostrate female section Seeds: pale or red-brown nutlet about Life cycle: herbaceous perennial Seeds: contained in sausage-shaped mass of one-eighth inch long, base and edges Growth characteristics: forms dense clusters of nutlets surrounded by a protective casing; covered with white bony material interwoven mat, can be free floating or root- multitude of hairs around seeds enable long-distance Height: can reach 2½ feet ed in soil; flowering primarily April to October dispersal by wind Life cycle: herbaceous perennial or all year in southern parts of Florida Height: to 11 feet tall Growth characteristics: flowers Distribution: native to South America; Life cycle: perennial winter through spring in Florida; repro- throughout the entire southern United Growth characteristics: flowering primarily Janu- duces by seeds and vegetatively through States; margins of ponds and lakes, ary–June; spreads by seeds and fragmentation of rhizome growth streams, swamps, ditches, flooded fields rhizomes; grows rapidly Distribution: probably a native of Origin: non-native Distribution: native; T. latifolia – throughout North tropical America; Gulf Coast states from Comments: can be suppressed by America; T. domingensis – Delaware west to Kansas Florida to Texas; ponds, marshes, lakes, alligator-weed flee beetle or alligator-weed and California, south into tropical America; shallow streams, flooded areas stem-borer; grows primarily in fresh water, fresh and brackish waters of marshes, ditches, canals, Origin: non-native but can tolerate some salinity. During retention ponds and lakes Comments: can use other aquatic periods of low water, the weed can grow on Origin: non-native vegetation as a substrate to initiate muddy banks and other low areas. Comments: common along shorelines; an aggres- raft-formation which sometimes become sive invader of disturbed habitats with moist soils floating islands or mats Photos used with permission from the University of Florida/IFAS Center for Aquatic and Invasive Plants. CITRUS INDUSTRY • May 2013 19 Ann Murray, ©2001, UF Amy Richard, ©2005, UF Vic Ramey, ©2002, UF

MAIDENCANE MEXICAN PRIMROSE- PARAGRASS Panicum hemitomon WILLOW, LONG-FRUITED Urochloa mutica Leaves: 4 to 10 inches in length, one- (syn. Brachiaria mutica) PRIMROSE-WILLOW quarter to one-half inch in width, leaf upper Leaves: 4 to 13 inches in length, one- surface is rough and the lower surface is Ludwigia octovalvis Leaves: alternate, stalkless; blades half inch wide; very fine, sparse, hairs on smooth; sheath is smooth to hairy both leaf surfaces, or both surfaces can be Stem: narrow, 1½ to 6 feet in height; narrowly lance-shaped to somewhat football-shaped, 2 to 6 inches long and up smooth; a rim of hairs at the leaf collars roots at the nodes Stem: hairy at nodes, roots at lower Flowers: green, in narrow spikes, 4 to one-half inch wide, veins are prominent; soft hairs cover both sides of the leaves nodes inches to 1 foot long Flowers: seed head 5 to 10 inches in Seeds: about one-sixteenth inch long; Stem: erect, branched, entirely herba- ceous or herbaceous upward and woody in length, with several alternate branches; with pale tan, narrowly football-shaped, smooth numerous spikelets about one-tenth inch Height: typically 1½ to 3 feet tall the lower section Flowers: petals yellow, heart-shaped in length Life cycle: herbaceous perennial Seeds: about one-sixteenth inch long, Growth characteristics: flowering Seeds: light brown, shiny, nearly round, tiny; capsule several-angled, ribbed tan, minutely ridged, somewhat rounded at mainly in the summer; rhizomes form large tip, football-shaped stands, reproduces by seeds and vegeta- Height: 3 to 4 feet northward and to 9 feet tall southward Height: usually 3 to 6 feet tall, or tively by branching and rhizome fragments; sometimes stems to 15 feet long and grows in shallow water and will extend from Life cycle: herbaceous or woody perennial frequently leaning or creeping; stems can the shoreline upward, can form exten- lodge upward on other vegetation and reach sive colonies in uplands especially when Growth characteristics: flowering summer-fall northward, all year southward; 8 to 10 feet irrigated, often occurs in pure stands Life cycle: herbaceous perennial Distribution: native; New Jersey to reproduces from seeds Distribution: native plant; pantropi- Growth characteristics: flowering Florida and west to Texas mostly spring-summer; reproduces primar- Origin: native cal; from North Carolina to Florida and into eastern Texas; marshes, ditches, margins of ily by seeds or by rapidly growing stolons; Comments: has extensive creeping spreads horizontally into water, where it rootstocks (rhizomes); normally in shallow lakes, swamps Origin: non-native can form dense floating mats, and can even waters, it can grow to 8 feet or more tall to spread out many feet over paved surfaces keep pace with rising water Comments: typically found along shores; extensive growth of populations Distribution: native to Africa; from impairs flood control, navigation and recre- Florida to Texas in the United States; prefers ational uses, can crowd out native species moist soils and grows along ditch banks and shores Origin: non-native Comments: originally introduced as a forage grass

20 CITRUS INDUSTRY • May 2013 Ann Murray, ©1999, UF Amy Richard, ©2006, UF Vic Ramey, ©1999, UF PICKERELWEED SMARTWEED TORPEDO GRASS Pontederia cordata Polygonum hydropiperoides Panicum repens Leaves: stalked, erect, in clusters, growing Leaves: alternate; stalkless or nearly so; Leaves: blades flat or folded, one-quarter inch from rhizomes; stalk to 2 feet long, constricted just a papery tube sheaths the stem above leaf wide and 2 to 10 inches long, with very fine hairs on upper surface; leaf sheath is sparsely hairy below blade; blade 2½ to 9 inches long and 2¾ to bases; blade narrow and lance-shaped Stem: rigid, can reach many feet in length; 4¾ inches wide, varying in shape from lance- Stem: swollen at nodes, usually with long rhizomes; rhizome tips are very sharp- shaped to rounded to heart-shaped branched, viney, rhizomes often present pointed and torpedo-like (from which it gets its Stem: unbranched, hidden by leaves except Flowers: pinkish, greenish or white in common name). when flowering, and, similar to the leaf stalk, spike-like clusters at or near stem tip constricted just below the first node Flowers: whitish, small, stalked; in a Seeds: shiny, black or brown, three- Flowers: in a terminal spike which can have terminal, open, branched seed head; seed head angled nutlet, one-eighth inch long several hundred violet-blue or white flowers with usually 2 to 4 inches long Height: mostly 2 feet tall or less; plants yellow markings; two-lipped with six petals and Seeds: shaped like a football, smooth, shiny, can climb over old stems accumulated in six stamens of two sizes; each open for only with rounded ends, about one-eighth inch long one day wetlands reaching 4 feet or so Height: mostly 8 inches to 1 foot tall, but can herbaceous perennial Seeds: one-seeded, smooth; fruit ridged, dry Life cycle: reach 3 feet, erect or leaning Height: usually about 3 feet or less, but can be Growth characteristics: flowering spring- Life cycle: herbaceous perennial 6 feet tall fall; sprawling habit; reproduces by seeds, Growth characteristics: flowering mostly Life cycle: herbaceous perennial rooting from the nodes, and by rhizome frag- May–October; reproduces readily vegetatively and Growth characteristics: flowering mostly mentation; can quickly cover open wet soils by seeds; may extend over open water, commonly spring-summer; typically found growing vigorously Distribution: native; throughout most of forming large floating mats; can grow in almost in shallow water; reproduces primarily vegetatively the United States; found in shallow water any soil; requires moisture for germination; ex- by branching and fragmentation of rhizomes and of swamps, marshes, ditches, ponds and pands rapidly with irrigation or abundant rain less frequently from seeds floodplains Distribution: native in tropical and subtropi- Distribution: native; eastern United States and Origin: native cal areas of the world, probably introduced into into Canada; shallow waters of marshes, streams, Comments: typically forms thick, dense the United States; common in Gulf Coast states ditches, lakes populations from Florida to Texas; ponds, lakes and ditches Origin: native Origin: non-native Comments: can form extensive, almost pure Comments: terribly invasive, easily crowds stands out native species WATER PASPALUM Height: tips erect, usually less than 16 inches Paspalum repens tall Life cycle: herbaceous annual (syn. Paspalum fluitans) Growth characteristics: flowering usually Leaves: sheaths loose, with stiff, coarse May–November; rapid growth; stems often hairs, often spongy; blades flat, 4 to 10 inches submersed long and 1 inch wide or less Distribution: native plant; common West Stem: sprawling, spongy, rooting at the joints, Virginia to Florida to Kansas and Texas; margins often elongated, can reach nearly 2 feet in length of lakes, ponds, ditches, streams, marshes and Flowers: greenish, hairy, clustered on the swamps underside of the branches, about one-sixteenth Origin: native inch long Comments: can form thick extensive mats Seed head: 3.5 to 8 inches long; with 20 to impeding flood control, navigation and recre- 70 winged branches, one-half to 4 inches long ational activities Ann Murray, ©1999, UF CITRUS INDUSTRY • May 2013 21 Ann Murray, ©2001, UF Stacia Hetrick, UF/IFAS Ann Murray, ©1999, UF Osceola County Extension, 2009 WATER PENNYWORT WILD TARO Hydrocotyle spp. (Hydrocotyle umbellata, WEST INDIAN Colocasia esculenta H. bonariensis and H. verticillata) MARSH GRASS Leaves: all basal; stalks attached near Leaves: alternate; blades shiny green, blunt-toothed, Hymenachne amplexicaulis the middle of the blade, to 4 feet long, with almost round; stalks attached near the middle underneath Leaves: blades flat, to 14 inches long and a purplish band at tip; blades large, heart- the blade; although normally only an inch or two on land, 1½ inches wide, base heart-shaped and shaped, stiff, to 3 feet long and 1½ feet stalks can be up to 1 foot or more long in deeper water clasping the stem wide, upper surface dark green, velvety Stem: horizontally spreading, can be above or below Stem: floating and creeping with ascend- Stem: a bulb covered with leafy scales ground, or floating ing tips, spongy, rooting at the lower nodes producing a short, thick, vertical shoot Flowers: small, white to greenish white, at the upper Flowers: seed head spike-like, dense, Flowers: enclosed in a sheath, sheath end of the flower spike, on individual whorled stalks occasionally lobed at the base, about one- base green, sheath tip expanded and yel- (umbellata and bonariensis) or lacking stalks (verticil- quarter inch wide and to 20 inches long; lowish; flowers small, densely crowed on a lata), stalks simple H. umbellata, stalked branched H. individual flowers small and rough with stiff finger-like cluster; female flowers are near bonariensis, no stalks H. verticillata hairs the base and male flowers are grouped Seeds: paired nutlets, approximately one-sixteenth to Seeds: very narrow, about one-eighth above, tip sterile with no flowers one-eighth inch long, ribbed or ridged Seeds: fruit a small berry, several seeds inch long, tip sharply pointed Height: in shallow water or on land less than an inch per berry to several inches tall; in deeper water, can be over a foot Height: 2 to 5 feet tall Height: 1.5 to 5 feet tall Life cycle: herbaceous perennial Life cycle: herbaceous perennial Life cycle: herbaceous perennial Growth characteristics: flowering March–July; Growth characteristics: flowering in fall; Growth characteristics: flowering reproduces by seeds and vegetatively by fragmentation reproduces by seeds and stem fragmenta- January–August; reproduces via seeds and of the stem tion; can quickly and completely cover wet primarily from rhizomatous offshoots of the Distribution: native; H. bonariensis – outer Coastal pastures corm Plain, west from North Carolina into Texas; H. umbellata Distribution: probably native to the West Distribution: native of tropical Asia, now – Nova Scotia and Minnesota south into Texas; H. verti- Indies; West Indies, tropics of Central and pantropical and ranging into the subtropics; cillata – Coastal Plain and Piedmont, Massachusetts west South America; central and south peninsula Georgia west into Texas; throughout Florida; into California; all three range south from Texas into South Florida; low wet pastures, marshes, river grows in a wide range of dry to wet habitats, America; ponds, ditches, lakes, seeps, marshes, prairies, banks, wet ditches and other seasonally can form dense growth along shore displac- streams, frequent in lawns, gardens and flower beds flooded habitats ing native vegetation Origin: native Origin: non-native Origin: non-native Comments: grows from the shoreline and pro- Comments: adapted to fluctuating water Comments: it is grown for food and gresses outward into open water; floating mats can levels, can survive extensive periods of ornament; food must be properly prepared break off from shoreline plants; all three species can drought as the plant is poisonous; an astound- grow together in mixed populations; can become weedy ing number of color variations have been in many irrigated situations; grows best during cooler developed as it is an extremely popular seasons of the year ornamental plant SELECTED SOURCES and Agricultural Sciences, SP189. 1996. 260 pp. in Florida’s Natural Areas. K.A. Langland, H.M. Aquatic Weed Identification and Control Man- Florida Wetland Plants – An Identification Cherry, C.M. McCormick, and K.A. Craddock ual. A.P. Burkhalter, L.M. Curtis, R.L. Lazor, Manual. J.D. Tobe, K.C. Burks, R.W. Cantrell, Burks. University of Florida, Institute of Food and M.L. Beach, and J.C. Hudson. Florida Depart- M.A. Garland, M.E. Sweeley, D.W. Hall, Agricultural Sciences Communication Services. ment of Natural Resources. Bureau of Aquatic P. Wallace, G.A. Anglin, G. Nelson, J.R. Cooper, 2008. 193 pp. Plant Research and Control, 1972, 100 pp. D. Bickner, K. Gilbert, N. Aymond, K. Green- Identification Manual for Wetland Plant Florida Freshwater Plants – A Handbook of wood, and N. Raymond. University of Florida, Species of Florida. R.L. Dressler, D.W. Hall, Common Aquatic Plants in Florida Lakes. M.V. Institute of Food and Agricultural Sciences. K.D. Perkins, and N.H. Williams. University Hoyer, D.E. Canfield, Jr., C.A. Horsburg, and 1998. 598 pp. of Florida, Institute of Food and Agricultural K. Brown. University of Florida, Institute of Food Identification & Biology of Non-Native Plants Sciences, SP-35. 1987. 308 pp. Stephen Futch is a multi-county citrus Extension agent at the Citrus Research and Education Center in Lake Alfred; Kenneth Jones is a senior biological scientist in the Center for Aquatic and Invasive Plants at the Citrus Research and Education Center in Lake Alfred; David Hall is a botanist in Gainesville. 22 CITRUS INDUSTRY • May 2013