Juncus conglomeratus

Compact Rush
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Clade:	Commelinids
Order:	Poales
Family:	Juncaceae
Genus:	Juncus
Species:	J. conglomeratus
Binomial name
Juncus conglomeratus L.
Synonyms [1] [2]
Juncus leersii T.Marsson Juncus matthioli Bubani Juncus subuliflorus Drejer Juncus effusus var. conglomeratus (L.) Engelm.

Juncus conglomeratus, the compact rush, is a perennial, herbaceous flowering plant species in the rush family Juncaceae.

In the British Isles it is one of six rush species that can dominate lowland damp grasslands. ^{[3] [ citation needed ]} In New Zealand, its habitats include lake margins, roadside drains and wet pastures. ^[4]

Distribution

The species' geographical range includes the northwestern corners of Africa, almost all of Europe and the Caucasus region. It has been introduced and has become wild in Australia, New Zealand and North America. ^[5]

Description

Juncus conglomeratus forms large, dense tufts up to 1.2 m high with a dense bundle of roots.

Its stems are awl-shaped, stalked, vivid green, partially filled with a core (continuous, uninterrupted core), wrapped at the base (below ground level) with scaly brown leaf sheaths. The stems beneath the inflorescence are ribbed, while in the similar Scattered rush (Juncuseffusius) they are smooth.

The plant's leaves are exclusively abaxial, stalk-like.

The Inflorescence is a spherical head, about 1 cm long. Appears lateral because at the base a pituitary grows as an extension of the stem. ^[6]

The flower is small, 2-2.5 mm long, perianth - rust-colored, stamens count ranges from 3-6. Blooms from June to August.

The fruit forms a capsule, with a small beak at the tip, length ranging from 1.5–3.2 mm. ^[7]

Seeds are small (up to 0.3 mm long), dark brown, egg-shaped oblong, laterally flattened, pointed at the end, dull. The weight of 1000 seeds is 0.01 g.

Close-up of inflorescence

Variability

It has been observed to hybridize with Juncus effusus, Juncus inflexus and Juncus filiformis.

References

1. POWO. 2024. Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Available at: http://powo.science.kew.org/.
2. NatureServe Explorer, available at: https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.153778/Juncus_conglomeratus
3. The Lowland Grassland Management Handbook Archived 2011-03-17 at the Wayback Machine 2nd edition, A Crofts and R G Jefferson (eds) English Nature ISBN   1-85716-443-1, 1999
4. "Juncus conglomeratus". New Zealand Plant Conservation Network. Retrieved 2025-07-05.
5. "Taxonomy Detail GRIN-Global". npgsweb.ars-grin.gov. Retrieved 2025-07-04.
6. "Juncus conglomeratus (bunch-flowered soft rush): Go Botany". gobotany.nativeplanttrust.org. Retrieved 2025-07-05.
7. "Juncus conglomeratus". New Zealand Plant Conservation Network. Retrieved 2025-07-05.