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Typha

See list of 2 species in this genus

Leaf blades shrink considerably in drying, and users of this key are warned to follow measurements carefully in the following key. Also, carpellate spike measurements are for fruiting individuals, and measurements may be narrower on individuals collected prior to maturation. Leaf mucilage glands can be difficult to detect in fresh material, so it is best to dry specimens before judging their conspicuousness. In order to confidently identify plants (especially when hybrids may be present), examination of flowers and associated micromorphological structures is crucial, where 20 × or higher magnification is useful. The carpellate bracteoles, found in Typha angustifolia and its hybrids, appear as clavate-shaped structures with a truncate and thickened apex (as opposed to the carpellate flowers, which are more fusiform and taper at each end). The staminate scales are very narrow and appear 
to be stamen filaments on quick examination (but they do not support an anther). Hybrid plants are generally sterile and produce few or no seeds and have abortive pollen. Reference: 
Smith (2000).

  • 1a. Carpellate spikes (20–) 24–36 mm thick in fruit; leaves glaucous when fresh, the widest ones 10–23 (–29) mm wide when fresh, 5–20 mm wide when dry; compound pedicels on denuded inflorescence axis bristle-like, 1.5–3.5 mm tall [Fig. 309]; carpellate bracteoles absent; stigmas persistent on mature fruit, ovate to broad-lanceolate in outline, 0.1–0.2 (–0.25) mm wide at the widest point; carpellate spike and staminate spike contiguous, rarely separated by a gap as much as 4 cm; staminate scales colorless to stramineous; mucilage glands at transition from blade to sheath usually colorless, obscure
  • 1b. Carpellate spikes 13–22 mm thick in fruit; leaves not glaucous, the widest ones 4–12 mm wide when fresh, 3–8 (–10) mm wide when dry; compound pedicels on denuded axis peg-like, 0.5–0.7 mm tall [Fig. 308]; carpellate bracteoles present; stigmas sometimes deciduous in fruit, narrow-lanceolate in outline, 0.04–0.08 (–0.1) mm wide at the widest point; carpellate spike and staminate spike separated by a gap of 1–8 cm; staminate scales stramineous to medium brown; mucilage glands at transition from blade to sheath brown, visible in mid- to late season

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