Aquatic and Wetland Plants of Southeastern United States: Monocotyledons

Artificial Key to the Higher Taxa

Artificial Key to the Higher Taxa of Aquatic and Wetland Monocotyledonous Plants of Southeastern United States 1. Plants diminutive, floating on or submersed in water, stranded on mud or on debris in wet places, plant body not differentiated into stems and leaves, thalluslike, rootless or with 1-few simple roots. Lemnaceae, p. 464 1. Plants with stems and leaves, leaves sometimes scalelike, sometimes reduced to sheaths circling the stem. 2. Marine aquatic plants. 3. Leaves opposite, in 1-3 pairs at or near the apex of short, erect branches from a rhizomatous base (genus Halophila of). Hydrocharitaceae, p. 65 3. Leaves alternate. 4. The leaves ribbonlike or straplike, about 1 cm wide, borne closely set on short, vertical shoots from rhizomatous bases (genus Thalassia of). Hydrocharitaceae, p. 65 4. The leaves much narrower, terete or flat and threadlike. 5. Blade of leaf terete or subterete (genus Cymodocea of). Cymodoceaceae, p. 32 5. Blade of leaf flat. 6. Tip of leaf blade (in unbroken leaves) with a broad median tooth and a small lateral tooth either side of the median (genus Halodule of). Cymodoceaceae, p. 32 6. Tip of leaf blade obtuse or acute, not toothed. 7. Apex of leaf obtuse. Zosteraceae, p. 31 7. Apex of leaf acute. Ruppiaceae, p. 35 2. Fresh or brackish water aquatic or terrestrial plants. 8. Leaf blade large, fanlike (palmaceous). Palmae, p. 455 8. Leaf blade not fanlike. 9. Stem woody. 10. Leafy stem erect, smooth; internodes hollow (genus Arundinaria of). Gramineae, p. 217 10. Leafy stem climbing by tendrils terminating stipules; internodes solid (genus Smilax of). Liliaceae, p. 571 9. Stems herbaceous. 11. Plant a floating aquatic (unless stranded at low water); leaves in rosettes, broadly cunéate or cuneate-obovate, essentially truncate at the summit, densely short-pubescent; roots conspicuously feathery (genus Pistia of). Araceae, p. 456 11. Plant not as described above. 12. Plants aquatic, wholly submersed, partially submersed, or floating, but not with any parts appreciably emersed; (this small portion of the key designed to aid in identificationof forms commonly without inflorescences or flowers much of the time; if plants with inflorescences or flowers, they may be keyed, as well, from 2nd no. 12). 13. Leaves relatively short and closely set, not threadlike, the stems together with the leaves thus more or less cylindrical longitudinally. 14. The leaves mostly opposite, or in verticels (whorled). 15. Leaf bases sessile, not expanded and sheathlike (genera in). Hydrocharitaceae, p. 65 15. Leaf bases expanded and somewhat sheathlike. Najadaceae, p. 37 14. The leaves alternate and spirally arranged. Mayacaceae, p. 477 13. Leaves in rosettes, tightly clustered basally on short stems, or alternate, scattered on the stem, narrow and threadlike. 16. Plants floating. 17. Leaves with a central disc of purplish spongy tissue below; petiole not inflated (rosette stage of genus Limnobium of). Hydrocharitaceae,p. 69 17. Leaves without a central disc of spongy tissue below; petiole usually inflated (genus Eichhornia of). Pontederiaceae, p. 534 16. Plants not floating. 7 Palmae. p. 455 Cymodoceaceae. p. 32 Zosteraceae. p. 31 Ruppiaceae. p. 35 Artificial Key to the Higher Taxa of Aquatic and Wetland Monocotyledonous Plants of Southeastern United States I. Plants diminutive, floating on or submersed in water, stranded on mud or on debris in wet places, plant body not differentiated into stems and leaves, thalluslike, rootless or with I-few simple roots. Lemnaceae. p. 464 I. Plants with stems and leaves, leaves sometimes scalelike, sometimes reduced to sheaths circling the stem. 2. Marine aquatic plants. 3. Leaves opposite, in 1-3 pairs at or near the apex of short, erect branches from a rhizomatous base (genus Halophila of). Hydrocharltaceae. p. 65 3. Leaves alternate. 4. The leaves ribbonlike or straplike, about I cm wide, borne closely set on short, vertical shoots from rhizomatous bases (genus Thalassia of). Hydrocharltaceae. p. 65 4. The leaves much narrower, terete or flat and threadlike. S. Blade of leaf terete or subterete (genus Cymodocea of). S. Blade of leaf flat. 6. Tip of leaf blade (in unbroken leaves) with a broad median tooth and a small lateral tooth either. side of the median (genus Halodule of). Cymodoceaceae. p. 32 6. Tip of leaf blade obtuse or acute, not toothed. 7. Apex of leaf obtuse. 7. Apex of leaf acute. 2. Fresh or brackish water aquatic or terrestrial plants. 8. Leaf blade large, fanlike (palmaceous). 8. Leaf blade not fanlike. 9. Stem woody. 10. Leafy stem erect, smooth; internodes hollow (genus Arundinaria of). Gramlneae. p. 217 10. Leafy stem climbing...