Heteranthera, IN

KEY TO SPECIES OF HETERANTHERA IN View in CoL NORTH AMERICA (NORTH OF MEXICO)

1. Inflorescences monoflorous,stamens of similar size.

2. Leaves all linear,perianth yellow,anthers curling after anthesis _______________________________________________ H. dubia

2. leaves linear (on seedlings) or with distinct petiole and blade,anthers remaining straight to slightly falcate.

3. Leaves oblong to ovate,blade base truncate to cuneate;perianth arrangement actinomorphic,upper lobe without lateral flanges _____________________________________________________________________________________ H. limosa

3. Leaves rounded to oblong, blade base cordate to truncate;perianth arrangement zygomorphic,upper lobe with paired flanges________________________________________________________________________________ H. rotundifolia

1. Inflorescences 2-many flowered; stamens of two distinct sizes.

4. Leaves lanceolate to linear, no petiolate leaves produced; inflorescences elongating over several days, filaments obliquely swollen _________________________________________________________________________________ H. mexicana

4. Leaves with linear seedling leaves only,petiolate leaves abundant as seedlings,filaments linear.

5. Leaves on flowering plants distinctly cordate (length to width ratio 1–2); perianth mauve with darker blotches on upper central perianth lobe;filaments of lateral (smaller) stamens glabrous_____________________________ H. peduncularis

5. Leaves on flowering plants reniform to slightly cordate (length to width ratio 0.5–1); perianth white or lavender to purple with bilobed blotches green or brown to purple;filaments of lateral (smaller) stamens pubescent with long hairs.

6. Inflorescences with 5–15 flowers;the flowering stalk elongating well beyond the spathe apex on emersed inflorescences such that the apical flowers extend well beyond the spathe apex,perianth lobes lavender to purple _________________________________________________________________________________________ H. missouriensis

6. Inflorescences with 3–8 flowers;the flowering stalk elongating such that the terminal 1–2 flowers might extend beyond the spathe apex and some to most flowers are enclosed within spathe, perianth lobes white to pale lavender.

7. Leaves mostly rounded; apex obtuse to slightly acute; second internode of cincinnus less than 0.5 cm; hairs on lateral filaments purple____________________________________________________________________ H. pauciflora

7. Leaves distinctly reniform, apex obtuse; second inter node of cincinnus more than 0.5 cm long; hairs on lateral filaments white ______________________________________________________________________ H. reniformis