SEED-GERMINATION OF 2 CATTAIL (TYPHA) SPECIES AS A FUNCTION OF EVERGLADES NUTRIENT LEVELS

Sawgrass (Cladium jamaicense) is being replaced by cattails (Typha dom ingensis and Typha latifolia) in Water Conservation Area 2A (WCA 2A) o f the Florida Everglades. This replacement coincides with changes in n utrients in WCA 2A. Investigating seed germination of Typha in respons e to different nutrient levels, focusing on phosphate, might help in u nderstanding how this replacement occurs. Three sets of experiments wi th seed germination were conducted. Series I, a pilot study, was run t o set the parameters for further investigations using Typha domingensi s. Germination up to 100% was obtained. Series II used held water coll ected from three areas of WCA 2A that differed in the concentration of phosphate. These three areas represented high, medium, and low nutrie nt conditions with total phosphates that ranged from 0.200 to 0.008 mg /liter Distilled water was used to create a zero nutrient condition. T ypha domingensis and T. latifolia seeds were used. Little difference i n germination percentage was found between T. domingensis and T. latif olia. Germination began after three days, reaching 22% to 40% in seven days. In high nutrients, however, T. latifolia germinated faster. In Series III, distilled water was used that had phosphate levels added c orresponding to the concentrations found in WCA 2A. This water was use d in place of the field water, which was used in Series II. In Series III, only T. domingensis seeds were used. No difference was found in s eed germination as the phosphate concentration was varied. Germination began after three days, reaching about 40% in seven days. Seed and '' fruit'' traits were also measured. T. latifolia produced 1.4 times as many seeds as T. domingensis, but the mean seed weight of T. domingens is was 3.5 times that of T. latifolia. Results suggest that both catta il species can germinate under a variety of phosphate levels. Thus, bo th T. domingensis and T. latifolia may be long-term threats to areas i n the Everglades presently occupied by sawgrass.