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1 Leaves opposite or whorled, of two types, the aerial leaves larger and obovate to orbicular, < 1.5× as long as wide, the submersed leaves linear to orbicular; inflorescences terminal racemes or panicles
1 Leaves opposite, of one type, linear to oblanceolate or oblong, most > 3× as long as wide; inflorescences terminal racemes, axillary racemes, or axillary single flowers.
..2 Leaf margins white-cartilaginous; flowers mostly aggregated into axillary spikes or racemes or terminal racemes (rarely some on a plant axillary single flowers)