Het geslacht Alternanthera Forsk. in Nederland

Three species of Alternanthera, viz. A. sessilis (L.) DC., A. pungens H.B.K., and A. peploides (Humb. & Bonpl. ex R. & Sch.) Urb. have been found as aliens in the Netherlands. They may be distinguished as follows: 1. Tepals almost equal in form and size, without excurrent midrib, glabrous, white. .................... 1. A. sessilis 1’. Tepals distinctly unequal in form and size, at least partly with an excurrent midrib, more or less hairy, dirty white. 2. The two largest (abaxial) tepals ca. 4½-5½ mm long, with a spiny point which accounts for about 1/3 of their length. Filaments and pseudostaminodes shortly triangular ....................... 2. A. pungens 2’. The two largest (abaxial) tepals ca. 4 mm long, with short, less spiny point. Filaments and pseudostaminodes linear-subulate ........... 3. A. peploides