Alternanthera sessilis

(L.) R.Br. ex DC. (1813)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Eudicot-CoreEudicot Order: Caryophyllales Family: Amaranthaceae Genus: Alternanthera

sessile joyweed

Description

Key Characters:

Growth Form: Perennial herbs.

Stems: Stems prostrate, rarely ascending, often rooting at the nodes, 1–10 dm long, villous in lines and transversely at the nodes.

Roots:

Leaves: Leaves simple. Opposite. Blades obovate to broadly elliptic, occasionally linear–lanceolate, 1–15 cm long, 0.3–3 cm wide. Surfaces glabrous to sparsely villous. Margins entire. Petioles 1–5 mm long. Stipules absent.

Flowers: Flowers in sessile spikes. Flowers bisexual (perfect), actinomorphic. Each flower subtended by a bract and 2 bracteoles. Bract and bracteoles shiny white, 0.7–1.5 mm long, glabrous. Calyx of 5 sepals, equal, 2.5–3 mm long, outer ones 1–nerved or indistinctly 3–nerved toward base. Corolla (petals) absent. Stamens 5, 2 sterile. Ovary superior, 2–3(4)-carpellate, the carpels connate to form a compound, 1-celled ovary; ovule placentation basal, free-central, or rarely apical; style 1, often lobed.

Fruit: Urticles 2–2.3 mm long; exceeding the sepals. Seeds 1 per fruit; the surface usually lustrous; endosperm essentially absent.

Ploidy: 2n = 34; 36; 40; 96

Habitat:

Elevation Range:

Historical Distribution

Synonyms (52)

Uses and Culture

USES

  • Yes

Natural History

Statewide Status

Naturalized

Island Status

Kaua'i Naturalized
O'ahu Naturalized
Molokai Naturalized
Lana'i Naturalized
Maui Naturalized
Hawai'i Naturalized

Dispersal Agents


Pollinators

Bibliography

Name Published In: Cat. Pl. Horti Monsp.: 77 (1813)

Other References

Wagner et al. 1990:185 (O, Mo, M, H); Lorence et al. 1995:21 (K); Staples & Herbst 2005:100 (KEY), 101 (DESCR); Imada 2007:34 (L)

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Recorded By Record Number Island Source Date
1 Alternanthera sessilis Honolulu, Fair Grounds, fairway of short hole in Golf Links During rainy time, filled with water. Preserved_Specimen Neal, M.C. Oahu BISH 1938-02-20
2 Alternanthera sessilis 4090 Akemama Rd., Lawai Growing by trash can. Preserved_Specimen Wagner, W.L. 5623 Kauai BISH 1985-01-01
3 Alternanthera sessilis Honolulu, Bishop Museum courtyard. Preserved_Specimen Neal, M.C. Oahu BISH 1964-03-09
4 Alternanthera sessilis Koloa District; Hanapepe River at Ho Road crossing, Hanapepe Growing on river bank, wet area. Occasional. Preserved_Specimen Lorence, D.H. 5206 Kauai BISH 1987-05-05
5 Alternanthera sessilis Near Waimanalo junction, Kailua Roadside. Preserved_Specimen Fosberg, F.R. 10928 Oahu BISH 1935-06-28
6 Alternanthera sessilis Wailoa estuary, Hilo Floating near bank. Preserved_Specimen Stemmermann, R.L. 7176 Hawaii BISH 1987-07-25
7 Alternanthera sessilis Boulder beach, Waimanu Valley, Kohala Preserved_Specimen Stemmermann, R.L. 6885 Hawaii BISH 1984-02-16
8 Alternanthera sessilis Honolulu International Airport, received in a shipment from Singapore. Cultivated aquatic plant imported via Worldwide Aquatics, Honolulu, for a company in Texas Preserved_Specimen Hoe, W.J. 5337 Oahu BISH 1992-08-18
9 Alternanthera sessilis Moiliili, Corner of Coyne St. snd Kaialiu St. In irrigated, fully sunny flower bed. Preserved_Specimen Arthur, K. 169 Oahu BISH 2025-09-04
10 Alternanthera sessilis Hanapepe River Crossing, Hanapepe Town, Kauai, Hawaii Growing mauka of bridge on mucky wet banks. Preserved_Specimen Crago, L.M. 2005161 Kauai BISH 2005-08-03
11 Alternanthera sessilis Honolulu, back of Houghtailing and Vineyard Streets Cattle-grazed enclosure. Preserved_Specimen Egler, F.E. 37265 Oahu BISH 1937-08-18
12 Alternanthera sessilis East Maui, Hana District Coastal pasture lands SE of Ka`uiki from Kaihalulu Bay to Ka Iwi o Pele. Preserved_Specimen Flynn, T.W. 2536 Maui BISH 1987-10-22
13 Alternanthera sessilis Honolulu, Waikahululu, Nuuanu Stream at School Street Bridge Single plant in crevice of stone wall above stream. Preserved_Specimen Fosberg, F.R. 27095 Oahu BISH 1946-09-22
14 Alternanthera sessilis Honolulu, Bishop Museum courtyard Among laua`e. Preserved_Specimen Neal, M.C. Oahu BISH 1964-03-09
15 Alternanthera sessilis Manele Bay Emerging from cement curbside in Manele Bay beach parking lot. Preserved_Specimen Lanai Conservation Internship Program 3 Lanai BISH 2005-07-07
16 Alternanthera sessilis West side of Kawainui Marsh, Kailua Locally common in moving water. Preserved_Specimen Fosberg, F.R. 57428 Oahu BISH 1978-03-28
17 Alternanthera sessilis East Maui, Keanae Growing as a weed in a garden area. Preserved_Specimen Hobdy, R.W. 2525 Maui BISH 1986-02-26
18 Alternanthera sessilis Heeia Kea Boat Harbor Edge of parking lot, from saturated soil with standing water Preserved_Specimen Faccenda, K. 2698 Oahu BISH 2022-09-20
19 Alternanthera sessilis Albert H. Azevedo Field, jct. of Hihimanu St. and Kalanianaole Hwy in Waimanalo Roadside. Preserved_Specimen Wagner, W.L. 4828 Oahu BISH 1983-06-04
20 Alternanthera sessilis Behind Donkey Beach, between Kealia and Anahola In marshy ground. Preserved_Specimen Hume, L. 362 Kauai BISH 1988-10-23