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Myriophyllum Aquaticum (Vell.) Verdc Myriophyllum aquaticum (Vell.) Verdc. Parrot Feather (Enydria aquatica, Myriophyllum braziliense, Myriophyllum proserpinacoides) Other Common Names: Brazilian Water Milfoil, Parrot Feather Milfoil, Parrot Feather Watermilfoil, Parrot's- Feather, Water-Feather, Watermilfoil. Family: Haloragaceae. Cold Hardiness: Parrot Feather returns as a perennial in USDA zones 7(6) through 13, but is mostly evergreen where water does not freeze. Foliage: Four to six semi-evergreen to evergreen whorled leaves with simple pinnately filiform lobes are present at each node; blades resemble small blue-green to gray-green feathers ½ to 1¼ long; foliage is horizontally oriented relative to the stems in a foxtail fashion. Flower: Short spikes of tiny yellowish green to whitish green flowers are held just above the water's surface in 2 to 4 long spikes; this dioecious species is present only as female plants in the USA; flowers are not ornamental. Fruit: Fruit consist of tiny four-lobed nutlets, but not produced in our region due to lack of a suitable pollinator. Stem / Bark: Stems — the stiff sparsely branched slender stems are green, often flushed red; Buds — tiny, foliose, green; Bark — not applicable, a herbaceous perennial. Habit: Parrot Feather is a floating herbaceous perennial that grows from foxtail shaped stems, up to 15 long, which branch to form rafts with upturned tips a few inches above the water surface; on boggy soils they can root from the nodes to form groundcovers to about 12 tall; plants are very fine textured. Cultural Requirements: Parrot Feather is very easy to grow in almost any fresh water with adequate sun that does not freeze extensively, but it has not grown well for us in brackish water; plants will tolerate full to partial sun in bog lands or floating in still or slow moving open water. Pathological Problems: Few pests or diseases are significant problems on this species. Ornamental Assets: Handsome fine textured blue-green to gray green leaves which emerge slightly from the surface of the water create a lush tropical feel to water features; the dense growth provides habitat for various micro and macro invertebrates which are feed on by fish and various wildlife; decomposing portions of the plants contribute to the detritus, decomposed organic matter used by many aquatic invertebrates as food. Limitations & Liabilities: Plants can quickly become so vigorous that they overwhelm smaller bodies of water and tend to crowd out other water garden plants, requiring frequent maintenance to remove excess plants; these excess plants can provide too much shade to smaller water features. Landscape Utilization: Popularity of this species as a water garden plant has increased in recent years due to the handsome blue-green or grey-green foliage and vigorous growth habit, however it can be a victim of its own success and become a liability; although at the time this was written M. aquaticum was currently not a restricted plant as is closely related to M. spicatum which is a noxious weed; thus it would be wise to only use M. aquaticum with great care to prevent its escape to sensitive ecosystems in the region. Other Comments: Originally introduced in the aquarium trade, this species has also been planted in outdoor water gardens; the genus name derives from the Greek words myrios for many and phyllum for leaf; the specific epithet refers to its aquatic nature. Native Habitat: This South American native has naturalized in warmer portions of the USA, including Texas. Related Taxa: The genus Myriophyllum L. contains 14 or 15 species of water plants, all of which should be viewed with caution as several are invasive species in water bodies around the world. Ceratophyllum demersum L. Coon's Tail (Ceratophyllum apiculatum) • Coon's Tail is also known as Hornwort or Rigid Hornwort; this member of the family Ceratophyllaceae Gray resembles the Myriophyllum spp. in being a branched floating aquatic perennial plant with tubular shaped overall stems; however, these tubes are much smaller in diameter, shorter and more densely branched, and leaves are a dark green color in comparison to the Myriophyllum spp. • This species is native to North America and might be a suitable more ecologically friendly substitute for Myiophyllum spp. for aquariums and water garden use; the genus name derives from the Greek words keras for horn and phyllum for leaf in reference to the horned appearance of the submerged leaves, the specific epithet derives from the Greek word for a chain, probably in reference to the stems. Egeria densa Planch. Brazilian Waterweed (Anacharis densa, Elodea densa, Philotria densa) • This member of the family Hydrocharitaceae Juss., also known as Brazilian Elodea, Dense Waterweed, Egeria, Large-Flowered Waterweed, or Leafy Elodea, is native to South America, but naturalized throughout much of the Southeastern USA, including Texas; the specific epithet refers to the more densely spaced leaves in comparison to related species. • Eregia densa resembles the Myriophyllum spp. in being a branched floating aquatic perennial, but is usually rooted in the soil at the base and has whorls of three linear to lanceolate dark green ½ wide by ¾ to 1¼ long leaves with much stouter stems what are not extensively exposed between the whorls of leaves as with Ceratophyllum or Myriophyllum; Egeria densa differs from Elodea in having larger leaves in whorls of four to six 3 rather than threes; the white /8 to ¾ three petaled flowers of Egeria are larger than those of Hydrilla, but are still not particularly ornamental. Elodea canadensis Michx. Elodea (Anacharis canadensis, Elodea brandegeeae, Elodea ioensis, Elodea linearis, Elodea planchonii, Philotria canadensis, Philotria linearis) • This member of the family Hydrocharitaceae, also known as Canadian Waterweed Canadian Pondweed, Ditchmoss, or Waterthyme, is native to much of North America, but is not considered to be native to Texas by some authorities; the genus name orginates from the Greek word for a marsh, elodes, and the specific epithet refers to this species nativity to Canada. • Elodea canadensis resembles Egeria densa, but has fewer dark green leaves per whorl, in threes, which are smaller and blade or falcate in shape; leaves are usually less than ¼wide and ½ to ¾ long; like Egeria densa, Elodea canadensis is a rooted perennial plant with floating stems which can survive in water when detached, so are found free floating at times; flowers of Elodea are smaller than those of Brazilian Waterweed and are also not considered to be particularly ornamental. Hydrilla verticillata (L. f.) ??? Royle Waterthyme (Ceratophyllum apiculatum) • This member of the family Hydrocharitaceae, also known as Hydrilla, Florida Elodea, Indian Star-Vine, or Wasserquirl, is considered an official noxious weed throughout the United States and by the state of Texas; it resembles the Myriophyllum spp. in being a branched floating aquatic perennial, but has whorls of three linear to lanceolate dark green ½ wide by ¾ to 1¼ long leaves with much stouter stems what are not extensively exposed between the whorls of leaves as with Ceratophyllum or Myriophyllum; Hydrilla verticillata can be further distinguished from Ceratophyllum, Elodia, Egeria, Myriophyllum by the presence of teeth on the midrib of Hydrilla which make it feel rough when stroked form base to tip. • The genus name for this species derives from the Greek word hydro for water, while the specific epithet means whorled, in reference to the leaves; it is illegal to grow or sell Hydrilla verticillata in Texas and it should not be used in aquariums or water gardens. Myriophyllum spicatum L. European Milfoil • European Milifoil, also known as Eurasian Milfoilm, Eurasian Watermilfoil, or Spiked Water Milfoil, is a notoriously aggressive species of floating water plant which is considered a noxious weed in most the United States, including the state of Texas where it is a restricted plant; this native perennial native to Europe, Asian, and Africa was often sold in the aquarium trade, it has escaped to become a major weed in many bodies of water around the world; it typically reproduced vegetatively with new colonies beginning whenever a piece breaks free and floats away, but tiny tan brown seeds may be produced on female plants. • Myriophyllum spicatum is typically lighter green in color than M. spicatum and has even more sparse filiform foliage; the whorls of three to five pinnately lobed leaves occur at regular intervals and elongate to a vary uniform length along the long sinuous stems resulting in the look of sparsely branched green tubes of floating feathery leaves; the multi-branched green stems are often flushed red. • European Milifoil is even messier in aquariums and water features than M. aquaticum and would be a poor water garden choice even if it were not considered a noxious weed and legally restricted; the specific epithet means spike-like. References: Diggs et al., 2006. Copyright 2011 by Michael A. Arnold with all rights reserved; intended for future inclusion in Landscape Plants For Texas And Environs, Fourth Edition. .
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