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Ruellia simplex

C.Wright (1870)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Eudicot-Asterids Order: Lamiales Family: Acanthaceae Genus: Ruellia

Mexican petunia

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Description

Key Characters:

Growth Form: Erect perennial herbs.

Stems: Lower stems sometimes becoming somewhat woody, 0.5–1 m long.

Roots:

Leaves: Leaves simple. Opposite and decussate (pairs of leaves alternating 90 degrees between nodes). Blades linear-elliptic to linear-lanceolate, 8-22 cm long, 0.8-1.5 cm wide. Surfaces glabrate, green; lower surfaces conspicuously paler. Margins entire. Petioles 20–24 mm long. Stipules absent.

Flowers: Flowers in cymose panicles. Flowers bisexual (perfect). Each subtended by 2 linear bracts 3–7 mm long. Calyx lobes 5, linear, 8–12 mm long. Corolla 5-lobed, large and showy, lavender, the throat purple, 4–4.5 cm long. Stamens 4, in pairs, inserted on the corolla alternate with the lobes, sometimes 1 or more reduced to staminodes; anthers dithecal, opening by longitudinal slits. Ovary superior, 2-carpellate; ovule placentation axile; style filiform, simple.

Fruit: Capsules with two cells; usually dehiscing explosively; ellipsoid; 2–2.5 cm long; glabrous. Seeds 4–20; On small hooked stalks (modified funiculus) that ejects the seeds from the capsule; embryos usually large; endosperm absent.

Ploidy: 2n = 34

Habitat: Now naturalized and often found in dry habitats such as cracks in sidewalks and disturbed; shaded gulch bottoms.

Elevation Range:

Historical Distribution

Images

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Uses and Culture

USES

Natural History

Statewide Status

Naturalized

Island Status

Kuaihelani (Midway Atoll) Only found in cultivation
Kaua'i Only found in cultivation
O'ahu Naturalized
Molokai Potentially naturalizing
Maui Naturalized

Dispersal Agents

Water/Ocean
Other Animals

Vegetative Reproduction

Pollinators

Notes

  • Description digitized by Pumehana Imada
  • Native to Mexico; in Hawai‘i cultivated as an ornamental but easily escaping. This species is sometimes confused with Ruellia malacosperma Greenm., which does not occur in Hawai‘i, and differs from R. brittoniana in having shorter lanceolate

Bibliography

Name Published In: Anales Acad. Ci. Méd. Habana 6: 321 (1870)

Other References

Wagner et al. 1990:174 (Mi, K, O [as R. brittoniana]); Oppenheimer & Bartlett 2002:2 (WM); Staples & Herbst 2005:91 (KEY, DESCR); Murugan et al. 2014:426 (Syn. R. brittoniana = R. simplex)

Wagner, W. L., Herbst, D. R., & Sohmer, S. H. (1999). Manual of the Flowering Plants of Hawai'i, Vols. 1 and 2 (No. Edn 2). University of Hawai'i and Bishop Museum Press.

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Description Recorded By Record Number Island Source Date
1 Ruellia simplex Kaunakakai, outside town to W along road Random plants in Mesembryanthemum. Preserved_Specimen Flowers blue. Oppenheimer, H.L. 70122 Molokai BISH 2001-07-14
2 Ruellia simplex [Hawaiian Islands; U.S.A.; O`ahu; Hawai`i; Honolulu] Preserved_Specimen Oahu BISH 1953-10-01
3 Ruellia simplex growing along the Nu'uanu stream adjacent to Lili'uokalani Botanical Garden along stream banks Preserved_Specimen perennial herb, ca. 40-45 cm tall, corolla purple Ross, M.C. 1957 Oahu BISH 2023-07-05
4 Ruellia simplex Honolulu, Waikahululu, Nuuanu Stream at School Street Bridge Cement stream bed. Preserved_Specimen Tangled herb up to 0.8 m tall, flowers blue-violet. Fosberg, F.R. 27098 Oahu BISH 1946-09-22
5 Ruellia simplex Honolulu, Kamehameha Girls' School Preserved_Specimen Judd Jr., A.F. Oahu BISH 1937-09-25
6 Ruellia simplex Kipapa; Army Nursery Preserved_Specimen Neal, M.C. Oahu BISH 1946-07-30
7 Ruellia simplex Honolulu, Kamehameha Girls' School Preserved_Specimen Judd Jr., A.F. Oahu BISH 1937-09-25
8 Ruellia simplex Wailuku, Reservoir #74, E of Maui Community Correctional Center, Wetland habitat. Preserved_Specimen Monoculture in the wetland site, covering ca. 2 acres. Flowering, fruiting, and spreading. Caraway, V. Maui BISH 2001-01-17
9 Ruellia simplex Honolulu: Manoa Valley; University of Hawaii Manoa Campus, along Manoa Stream Naturalized, common along stream. Preserved_Specimen Herb to sub-shrub with blue flowers. Herbst, D.R. 5299 Oahu BISH 1975-05-09
10 Ruellia simplex W Maui, Lahaina District, Lahaina Town Volunteers in yard and at edge of pavement. Preserved_Specimen Flowers purple. Oppenheimer, H.L. 70094 Maui BISH 2000-07-17
11 Ruellia simplex Mokuleia Beach; Degener garden Persistent in garden after cultivation. Preserved_Specimen Degener, O. 35271 Oahu BISH 1980-05-01
12 Ruellia simplex Honolulu: Bishop Museum, maintenance area Preserved_Specimen 50 cm high herb; flower color aster violet. Fragrance none (noon). Lau, J. 1104 Oahu BISH 1985-06-17
13 Ruellia simplex Koolau Mts., Fort Shafter, southern confluences of Kahauiki Stream. Open canopy of just-cut Pithecellobium dulce; understory of Panicum maximum, Cyperus involucratus, Commelina diffusa. Preserved_Specimen Herb ca 70 cm tall; flowers light blue to purple. Single adventive plant seen. Kawelo, K. 518 Oahu BISH 2019-06-24
14 Ruellia simplex Honolulu Preserved_Specimen Herb 2' tall; flower purplish blue. St.John, H. 10515 Oahu BISH 1930-04-28
15 Ruellia simplex Mokuleia Beach; Degener garden Persistent in garden after cultivation. Preserved_Specimen Degener, O. 35271 Oahu BISH 1981-05-26
16 Ruellia simplex Relict garden plant (?) at site of Mana Sugar Camp, jct of Hwy 50 and Mana Rd Preserved_Specimen Showy perennial to 60 cm tall; stem grn, purplish at nodes, glossy; lvs dull grn above and below, below w/midrib paler; inflorescence calyx grn w/white hairs; corolla w/base of tube pale violet and grn, tube above and petals blue-violet w/darker spot in throat. Hume, L. 432 Kauai BISH 1989-10-18
17 Ruellia simplex Kaimuki, Honolulu Preserved_Specimen Oahu BISH 1937-01-01
18 Ruellia simplex Waimea Arboretum Preserved_Specimen herb to 1.2m; flowers purple Annable, C.R. 3712 Oahu BISH 1997-09-08
19 Ruellia simplex Honolulu, 3797 Diamond Head Circle Preserved_Specimen Flower blue. Neal, M.C. 2 Oahu BISH 1963-04-20
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