Description:

• Robust aquatic shrubs up to 2 m tall, forming dense, strongly rooted stands, stoloniferous and caulescent with leaves in dense, apical rosettes
• Stems persistent, branched at base, densely covered with reticulate, fibrous, dark leaf remains
• Leaves linear-acuminate, ± 1 m long, margin and keel sharply serrate to serrulate, with a tubular sheathing base
• Inflorescence a large, much-branched terminal panicle on a long, trigonous peduncle; each branchlet bearing few- to many-flowered lateral fascicles supported by funnel-shaped, caudate bracts diminishing in size upwards
• Flowers bisexual, regular, small, pedicellate
• Perianth 3 + 3; segments free, equal, ovate, rigid, brown
• Stamens 3 + 3, as long as perianth segments or longer and exserted; filaments filiform; anthers oblong, basifixed, with opposing thecae opening lengthwise
• Ovary superior, 3-locular, ovoid, with 3-6 ovules in each locule on axile placentas; style short or 0; stigmatic branches long, papillate
• Capsule enclosed in perianth, ovoid-acute, 3-valved
• Seeds 1 or 2 per locule, ovoid-oblong

Classification Notes:

• Prionium was originally included in the family Juncaceae. Research based on anatomy, morphology and rbcL sequence data indicates that Prionium should be placed in a family of its own (Cutler, 1969; Plunket et al., 1995; Munro & Linder, 1998).
• The new monotypic family Prioniaceae S.L.Munro & H.P.Linder was therefore erected (Munro & Linder: 51; 1998)

Nomenclature:

• Prioniaceae
  • None provided for family - See genus Prionium E.May

Distribution & Notes:

• Southern Africa: Genus 1, species 1, endemic to the Western and Eastern Cape as well as S KwaZulu-Natal

References:

• CUTLER, D.F. 1969. Juncaceae. Anatomy of the monocotyledons IV. JUNCALES. Clarendon Press, Oxford
• PLUNKET, G.M., SOLTIS, D.E., SOLTIS, P.S. & BROOKS, R.E. 1995. Phylogenetic relationships between Juncaceae and Cyperaceae: insights from rbcL sequence data. American Journal of Botany 82,4
• MUNRO, S.L. & LINDER, H.P. 1998. The phylogenetic position of Prionium (Juncaceae) within the order JUNCALES based on morphological and rbcL sequence data. Systematic Botany 23,1

Resources:

• Prioniaceae genus: Prionium