Word of the Week: Stolon

stolon [ stoh-luhn ] noun: a long horizontal plant stem or branch (runner) that arises from the central rosette and droops to the soil, where it may form another plantlet from nodes or buds at its tip

Stoloniferous plants have runners (stems creeping horizontally usually above ground) that take root at the stem nodes, forming colonies (genets) of clones of the parent plants. The stem between the nodes, an internode, transports resources to each individual ramet (clone). In some cases internodes may wither once the ramet is established. If an unrooted ramet is severed from the stolon, its chances for survival increase when attached to a basal internode and the longer the internode, the better its prospects.

You know Saxifraga stolonifera (strawberry geranium) has stolons by its epithet. However, its common name deceives as it is neither a strawberry nor a geranium. Nevertheless, this non-native serves as an attractive ground cover or house plant. Photo © Elaine Mills

Common perennials that have stolons include Fragaria (strawberry), which usually demonstrates “guerrilla morphology characterized by clonal plants that are widely dispersed on the stolon with extensive spreading.” (Tworkoski 2000) While cultivated strawberries are a favorite fruit and profitable agricultural product, Fragaria virginiana, a native wild strawberry, may be regarded by some as a lovely ground cover and by others as a weed. Little may they know that it is one of the two species–the one that provides the flavor–used to create the hybrid strawberries found in food markets. Its small edible fruits are useful to wildlife and the plant can be used on slopes to prevent erosion. Sometimes confused with native wild strawberry, Potentilla indica, formerly Duchesnea indica, (Indian-strawberry or mock strawberry) is an invasive weed (on the Arlington County Non-Native Invasive Plants list) that also spreads by stolons. It is attractive, with small edible but tasteless fruits.

Which is native wild strawberry? Which is invasive Indian-strawberry?

 

Other stoloniferous plants to be avoided are Glechoma hederacea (ground ivy), Lamiastrum galeobdolon (yellow archangel), and Vinca minor and Vinca major (vinca or periwinkle). Although listed by many government agencies as invasive, these (semi) evergreen plants are still sold in nurseries. The stolons that make these plants useful as ground covers also contribute to their tendency to spread aggressively and invade beyond their intended limits. The common lawn and garden weed, Veronica spp. (speedwell) also spreads via creeping stolons.

Some Stloniferous Ground Covers on the Arlington and/or Alexandria Non-Native Invasive Plants Lists

Plants whose spread is regarded as a positive factor include several forms of phlox, such as Phlox stolonifera (creeping phlox, whose epithet means “having stolons”) and Phlox divaricata (woodland phlox). The latter blooms on erect, 12–18-inch stems in spring. This form can be ephemeral and the fertile stems may die back in early summer leaving non-flowering runners, which spread as a semi-evergreen ground cover.

Many grasses also spread via stolons. If you want a species to spread to strengthen a lawn, then stoloniferous spread is an advantage. If you want to get rid of that species and regard it as a weed, stolons make this more difficult, though mowing can help control the tendency to spread.

Stolonilierous and rhizomatous plants can exhibit “guerrilla growth,” acting as invaders spreading quickly to find and colonize more inviting habitats and “phalanx growth,” a defensive strategy to protect against invaders by establishing a dense, impregnable colony. Diagram is illustrative and does not depict a specific species. © Mary Free

Stoloniferous grasses include Buchloë dactyloides (buffalograss), Agrostis stolonifera (creeping bentgrass), Poa pratensis (Kentucky bluegrass), and Stenotaphrum secundatum (St. Agustine grass). Grasses and sedges that spread by both stolons and rhizomes include Cynodon dactylon (Bermudagrass), regarded as both a valued turf grass and a noxious weed, invasive Agrostis capillaris (colonial bentgrass), Paspalum vaginatum ‘Sw.’ (seashore paspalum – valued for its salt tolerance), Zoysia spp. varieties, and Carex pensylvanica (Pennsylvania sedge).

References

Booth BD, Murphy SD, Swanton CJ. 2003. Weed Ecology in Natural and Agricultural. CABI Publishing. ISBN 0-85199-528-4 S. https://www.cabi.org/isc/FullTextPDF/2003/20033037775.pdf.

Daniel K, Lerner R. 2018. Spreading Ornamental Plants: Virtues & Vices. HO-295-W. Purdue Extension. https://www.extension.purdue.edu/extmedia/HO/HO-295-W.pdf.

Rhizomes and Stolons, Forage Information System, © 2021 Oregon State University. https://forages.oregonstate.edu/regrowth/how-does-grass-grow/developmental-phases/vegetative-phase/rhizomes-and-stolons.

Tworkoskia TJ, Benassib TE, Takeda F. 2001. The effect of nitrogen on stolon andramet growth in four genotypes of Fragaria chiloensisL. Scientia Horticulturae 88:97–106 https://www.ars.usda.gov/ARSUserFiles/80800000/FTakeda/Benasi%20etal%20article.pdf.

 

 

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