noun
Trapa incisa; a species of water caltrop
A specific aquatic plant closely related to the water caltrop (菱). Used in botanical contexts.
ヒメビシは水田や池に生える水生植物です。
Trapa incisa is an aquatic plant that grows in rice paddies and ponds.
この池ではヒメビシの実を見ることができます。
You can see the nuts of Trapa incisa in this pond.
菱 (water caltrop) is a more common and broader term; ヒメビシ is a specific species within the same genus.
The name combines 姫 (hime, 'princess' or 'small and delicate') with 菱 (bishi, 'water caltrop'), referring to a smaller or more delicate species of water caltrop. The exact derivation is uncertain.