Growing in wet or muddy habits, these plants can grow in up to 30cm of freshwater. The rhizomes have long been used as a carbohydrate source and can be easily propagated. White flowers are borne in whorls of 3 on tall racemes in summer.
Sagittaria lancifolia (Bulltongue Arrowhead, Duck Potato) [sometimes S. latifolia]
Family: Alismataceae
Subspecies: subsp. lancifolia, subsp. media
Native: southeastern United States, Texas to Florida
Hardiness Zones: 8-11 (sources provide variable information, typically reliable source (MoBot) indicates zone 5 with protection)
Height: to 1.3m (rarely 2m)
Diameter: rhizomes to 0.6m long and 10cm wide
Root System: fibrous emerging from tuber-like rhizome, float if removed from soil-mud medium
Growth Rate: moderate-fast
Age: perennial forb/herb
Deciduous: yes
Monoecious/dioecious: monoecious with imperfect flowers
Monocot/dicot: monocot
Tolerates: wet soil, flooding soil
Problems (major): drying out is typically fatal
Problems (minor): low saltwater tolerance, requires high amounts of sun for blooming
Poisonous: no, rhizome safely edible
Soil requirements: naturalize in sandy, loamy, and muddy soils, must be consistenly wet or submerged
Air requirements: good soil aeration not vital
Watering requirement: must be in consistently wet habits
Sun requirement: full sun
Leaves: to 1m, sagittate-linear-ovate-elliptic lamina to 25cm (above water), petioles terete to 58cm, lanceolate or bladeless if submerged entirely, apex acuminte, base cuneate, venation parallel, glabrous
Flower structure: to 3cm in diameter, 3 sepals recurving and green, 3 petals white, stamens yellow and 6+ (in staminate flowers), pistils numerous and is bushy green clusters (for pistillate flowers), filaments longer than anhers, in 6-12 whorls of 3 flowers on racemes atop leafless scapes
Flowering frequency: June-August
Fruit type: achenes oblanceolate-obovoid, winged, to 2.5mm, seeds may take up to 2 years for germination
Fruit dispersal: waterfowl, water, (possibly) wind
Subterranean storage organ: elliptical rhizome
Notable characteristics:
The flowers can be quite showy when numerous. The edible rhizomes float to the water’s surface if removed from their muddy soil substrate.
Uses:
Some use this as a food source rich in carbohydrates; these are more commonly ornamental obligate wetland plants.
Sources used:
- http://plants.usda.gov/core/profile?symbol=SALA
- http://www.wildflower.org/plants/result.php?id_plant=SALA
- http://www.clemson.edu/extension/horticulture/nursery/remediation_technology/constructed_wetlands/plant_materia l/bulltongue_arrowhead.html
- http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=222000344
- http://web.fscj.edu/David.Byres/duckpot/duckpot.htm
- https://edis.ifas.ufl.edu/ag403
- http://regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Sagilanc
- http://www.lilypons.com/product/red-stemmed-sagittaria-lancifolia-ruminoides
- tropical-bog-aquatic-water-pond-plant/tropical-bog-plants
- http://www.fnps.org/plants/plant/sagittaria-lancifolia
- http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspxkempercode=a633
- http://www.gbif.org/species/5328895
- http://www.amjbot.org/content/85/4/513.abstract
- http://jcho.masgc.org/frames/data/sagittarialancifolia.html
All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.
Female flower, sitmgatic surface designed to maximize capture pollen
Foliage emerging from rhizome near Hydroctyle
Male (staminate) flowers
A Fascinating Green World 
Beautiful shots! Thanks for sharing!