Families of Vascular Plants - Botany 307F

Poales - Juncaceae

7 genera/430 species, the greatest generic diversity in the southern hemisphere. Herbs or thick-stemmed shrubs (Prionium). Graminoid habit, but note contrast with Cyperaceae and Poaceae with respect to flower structure (see diagram below) and fruit type. The gynoecium arises from three gynoecial primordia, and forms a compound ovary that matures into the usually many-seeded loculicidal capsule1 seen in the lab.

Flowers of Juncus balticus (14061 bytes)

Flowers of Juncus balticus.  Note way in which anthers of uppermost flower all dehisced; is this evidence of protandry?

Photo: M. Ferguson Royal Ontario Museum 1997

1. Capsule - A dry, dehiscent fruit that develops from a compound ovary. In contrast, follicles and legumes are dry dehiscent fruits that develop fromsimple ovaries.

The Juncaceae are nearly unique in possessing a two unusual cytological fearures that they share with the Cyperaceae (Ball et al. 2003):

  • (1) chromosomes with diffuse centromeres, such that chromosome breaks result in fragments that are not lost during meiosis
  • (2) post-reductional meiosis

Ontario native genera of Juncaceae:  Juncus, Luzula (cf. Zomlefer pp. 345-347)

The Flora North America treatment of the Juncaceae (Brooks & Clemants 2000) is available HERE:

Flora North America - Juncaceae


The Families of Flowering Plants
DELTA database in natural language

L. Watson and M. J. Dallwitz


Images from Botany at the University of Hawaii

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