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Parthenium hysterophorus

L. (1753)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Eudicot-Asterids Order: Asterales Family: Asteraceae Genus: Parthenium

false ragweed, santa maria

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Description

Key Characters:

Growth Form:

Stems:

Roots:

Leaves:

Flowers:

Fruit:

Ploidy:

Habitat:

Elevation Range:

Historical Distribution

Images

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Uses and Culture

USES

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: Sp. Pl.: 988 (1753)

Other References

Wagner et al. 1990:347 (K, Mo, M, H); Wagner & Herbst 1995:16 (O); Oppenheimer 2016:23 (L); Kari Bogner pers. comm. 2025 (L†, 2023)

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Description Recorded By Record Number Island Source Date
1 Parthenium hysterophorus Koloa District, Lawai Valley Plants of the Allerton Estate at Lawai-Kai. Preserved_Specimen Herb to 1.5 ft.; lvs. dull med. green above, dull, paler below w/ raised midvein; stem w/pale green raised ridges & darker green median stripes; ray florets five,white; disc florets very pale greenish-white, faintly scented (9 am). Flynn, T.W. 5597 Kauai BISH 1995-08-15
2 Parthenium hysterophorus Along Diamond Head Road at the turnoff into the crater. Preserved_Specimen Funk, E.J. Oahu BISH 1990-07-17
3 Parthenium hysterophorus Kealakekua Ranch Preserved_Specimen Kawasaki, A. Hawaii BISH 1960-06-03
4 Parthenium hysterophorus Ca. 2.5 mi S of Kailua above Kuakini Hwy Nr grazed a`a fields with Leucaena leucocephala-Triumfetta semitriloba-Synedrella association. Preserved_Specimen Hairy, branched herb 30-60 cm ht. Leaves at first in rosette then alternate along stem. Nagata, K.M. 2584 Hawaii BISH 1983-01-14
5 Parthenium hysterophorus East Maui, middle Auwahi In middle of jeep road. Preserved_Specimen Wagner, W.L. 5455 Maui BISH 1984-10-07
6 Parthenium hysterophorus Waianae Range, Lualualei, antenna field. Lowland dry habitat of kiawe, koa haole, grasses, and located next to Marsilea villosa. Preserved_Specimen Naturalized weed with small white flowers. Larbe patch of ca. 100 plants; seedlings present. Bolling, M. 4 Oahu BISH 2014-03-27
7 Parthenium hysterophorus Lihuee District, Hoary Heads, Kipu Kai Abundant, weedy composite of disturbed, dry areas. Assoc. with Messerschmidia, Lantana, Scaevola, Lepidium, Sesuvium & Heliotropium. Preserved_Specimen To 2 or 2.5 ft. tall, gray-green, pale foliage, white flowers. Herbst, D.R. 2908 Kauai BISH 1973-03-22
8 Parthenium hysterophorus South Kohala District. Collected east of Queen Kaahumanu Highway between Mauna Lani Drive and Puako turn off Dry area with scant vegetation; open grassland with scattered Prosopis pallida. Preserved_Specimen Funk, E.J. Hawaii BISH 1991-02-04
9 Parthenium hysterophorus East Maui, Wailuku District, along Haleakala Highway A roadside weed. Preserved_Specimen Hobdy, R.W. 2323 Maui BISH 1985-04-01
10 Parthenium hysterophorus Lower Makaha Valley roadside (UTM 582804, 2373350) Dry lowland roadside vegetation Preserved_Specimen .5 m tall herb. ray florets 5, petals white. Degree of hairiness of stems is variable. Lau, A. 2009020601 Oahu BISH 2009-02-06
11 Parthenium hysterophorus At town entrance, Maunaloa Along roadside. Preserved_Specimen Matayoshi, N. Molokai BISH 1986-07-07
12 Parthenium hysterophorus West coast, about 3 mi south of resort area. Along road paralleling coastline Introduced dryland vegetation. Preserved_Specimen Shrubby, 1 ft. tall. Corn, C. Molokai BISH 1994-05-01
13 Parthenium hysterophorus Puuwaawaa Remnant dryland forest. Preserved_Specimen Nagata, K.M. 3706 Hawaii BISH 1987-10-04
14 Parthenium hysterophorus Koele, across from stables, along unpaved rd to Keahikawelo and Kanepuu In disturbed area; localized but dense infestation Preserved_Specimen White flowered shrubs Oppenheimer, H.L. 31510 Lanai BISH 2015-03-24
15 Parthenium hysterophorus Wheeler Army Airfield. Enter via Lyman Gate, turn right when able and wrap around until parallel with Kunia Road; drive between buildings and fence/hwy; go through chain gate; just past is a dirt pile. Soil pile contained several plants not frequently found on Wheeler Base. No canopy directly above. Other taxa in area include Spathodea campanulata, Leucaena leucocephala, Macaranga tanarius, Aleurites moluccana, Ficus spp. Understory: various grasses and herbs, mowed into a lawn: Urochloa maxima, Boerhavia coccinea, Chloris barbata, C. gayana. Preserved_Specimen Single large herb found. Adventive, not sure if it could naturalize or not. Beachy, J. 462 Oahu BISH 2017-02-13
16 Parthenium hysterophorus Wheeler Army Airfield. Enter via Lyman Gate, turn right when able and wrap around until parallel with Kunia Road; drive between buildings and fence/hwy; go through chain gate; just past is a dirt pile. Soil pile contained several plants not frequently found on Wheeler Base. No canopy directly above. Other taxa in area include Spathodea campanulata, Leucaena leucocephala, Macaranga tanarius, Aleurites moluccana, Ficus spp. Understory: various grasses and herbs, mowed into a lawn: Urochloa maxima, Boerhavia coccinea, Chloris barbata, C. gayana. Preserved_Specimen Single large herb found. Adventive, not sure if it could naturalize or not. Beachy, J. 462 Oahu BISH 2017-02-13
17 Parthenium hysterophorus Puuwaawaa Ranch at base of Puuanahulu Ridge near Mamalahoa Hwy Preserved_Specimen Herb with white flowers. Herbst, D.R. 5394 Hawaii BISH 1975-06-26
18 Parthenium hysterophorus Koolau Mts., Tripler. In grassy area next to road/parking lot. Preserved_Specimen Beachy, J. 554 Oahu BISH 2021-04-20
19 Parthenium hysterophorus Hwy. 56, ca. 0.25 mi S of Kauai Hilton, makai side of road Growing from curb. Preserved_Specimen Much branched herb ca. 70 cm. tall. Stem deeply grooved, pale green to yellowish. Leaf green with slight blue green tint, palest below. Flowers white, pentagonous when viewed from above, flattened, the five points formed by the five ray florets. Hume, L. 498 Kauai BISH 1990-03-21
20 Parthenium hysterophorus Maunaloa Town In lawn, by service station. Preserved_Specimen Hobdy, R.W. 2368 Molokai BISH 1985-04-23
21 Parthenium hysterophorus Ulupalakua, adjacent to Tedeschi Winery, NW of Puu Mahoe Preserved_Specimen Common roadside weed along dirt road, growing up to 4 ft. tall. Imada, C. 200233 Maui BISH 2002-07-16
22 Parthenium hysterophorus Near Okoe Bay, N of Kapua `A`a lava field. Preserved_Specimen Stemmermann, R.L. 7124 Hawaii BISH 1986-10-07
23 Parthenium hysterophorus Hanamaulu, along Hwy.56 near Peter Rayno, Sr. Park Preserved_Specimen Much branched, to 2.5 ft. high. Flowers greenish-white. Flynn, T.W. 999 Kauai BISH 1985-11-10
24 Parthenium hysterophorus Hanamaulu, along Hwy.56 near Peter Rayno, Sr. Park Preserved_Specimen Much branched, to 2.5 ft. high. Flowers greenish-white. Flynn, T.W. 999 Kauai BISH 1985-11-10
25 Parthenium hysterophorus East Maui, Wailuku District, along Haleakala Highway near 2 mile mark Preserved_Specimen Young plants forming low rosettes; flowering plants 2 ft. tall. Hobdy, R.W. 1753 Maui BISH 1983-04-19
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