Belongs within: Fimbristylis section Trichelostylis.
Day of the fimbry
Published 7 July 2025
Sedges are diverse but they are not considered easy to work with. About three hundred species are currently assigned to the sedge genus Fimbristylis, found in warmer regions around the globe. However, the exact number of species is uncertain; not only are they often difficult to distinguish, with much uncertainty which variants are the result of genetic isolation versus which are due to growth conditions, but most revisionary work has been focused on particular geographic regions. In general, though, Fimbristylis species bear inflorescences of single or clustered spikelets, with the glumes of each spikelet arranged spirally. Most glumes contain flowers, with only the basalmost glumes of a spikelet empty. Styles have an enlarged base that articulates with the ovary and is deciduous following fertilisation (Kern 1974). Embryos have the root cap displaced to a lateral position and the first leaf primordium in a basal location (Semmouri et al. 2019).
In a review of the Malesian species of the genus, Kern (1974) recognised eighteen sections (two of which, Abildgaardia and Actinoschoenus, are often treated as distinct genera). Among these, the type section Fimbristylis was recognised for species with two stigmas, fringed ligules, ovate glumes and trabeculate (with longitudinal ribs connected by cross-bars) nuts. However, revisions based on other regions have not always recognised any division into sections, and the correspondence between Kern’s sections and evolutionary relationships remains open to criticism.
Species within the section Fimbristylis are mostly distinguished by fine reproductive features such as the size and proportions of floral structures. Perhaps the most significant representative of the section is F. dichotoma, which has become distributed around the world as a result of human transport. Growth habit is highly polymorphic, and literally hundreds of synonyms have been established for this species at one time or another. In many places, F. dichotoma is regarded as a troublesome weed, though it is also used in some areas for livestock fodder. Fimbristylis bisumbellata, another widespread weed species in the Old World (particularly problematic in rice fields), is very similar to F. dichotoma but differs in being an annual rather than a perennial. Other species are more localised in distribution and have not achieved their relatives’ global success.
Systematics of Fimbristylis section Fimbristylis
Fimbristylis sect. FimbristylisG72 [incl. F. sect. DichelostylisB78]
|--*F. dichotomaME70, SB19 [incl. F. parvifloraB78]
`--+--F. aestivalisSB19 [incl. F. pallescensB78]
| |--F. a. var. aestivalisB78
| `--F. a. var. macrostachya non F. macrostachyaB78
`--F. squarrosa Vahl 1806SB19, ME70 (see below for synonymy)
Fimbristylis sect. Fimbristylis incertae sedis:
F. caespitosa [incl. F. brachylaena]B78
F. denudataB78
F. depauperataB78
F. diphylla [incl. F. communis, F. elongata, F. obtusifolia, F. polymorpha, F. stricta, F. variabilis]B78
|--F. d. var. diphyllaB78
`--F. d. var. gracilis [incl. F. royeniana]B78
F. elataB78
F. ferruginea [incl. F. brevifolia]B78
|--F. f. var. ferrugineaB78
`--F. f. var. foliata [incl. F. arvensis, F. paucispicata]B78
F. spirostachyaB78
F. latinucifera Govindarajalu 1972G72
Fimbristylis squarrosa Vahl 1806SB19, ME70 [incl. F. propinquaB78, F. velata Br. 1810ME70, F. squarrosa var. velata (Br.) Clarke in Cheesem. 1906ME70]
*Type species of generic name indicated
References
[B78] Bentham, G. 1878. Flora Australiensis: A description of the plants of the Australian Territory vol. 7. Roxburghiaceae to Filices. L. Reeve & Co.: London.
[G72] Govindarajalu, E. 1972. Studies in Cyperaceae—V. Novelties in Fimbristylis (L.) Vahl. Journal of the Bombay Natural History Society 69 (1): 159–164.
Kern, J. H. 1974. Cyperaceae. Flora Malesiana, Series I—Spermatophyta, Flowering Plants 7 (3): 435–753.
[ME70] Moore, L. B., & E. Edgar. 1970. Flora of New Zealand vol. 2. Indigenous Tracheophyta: Monocotyledones except Gramineae. A. R. Shearer, Government Printer: Wellington (New Zealand).
[SB19] Semmouri, I., K. Bauters, É. Léveillé-Bourret, J. R. Starr, P. Goetghebeur & I. Larridon. 2019. Phylogeny and systematics of Cyperaceae, the evolution and importance of embryo morphology. Botanical Review 85: 1–39.