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Family Myrtaceae
Redtop
Agrostis gigantea Roth
BLACK BENT GRASS
Hong zhu gao yun gan

Scientific names Common names
Agrostis alba subsp. gigantea (Roth) Arcang. Black bent (Engl.)
Agrostis alba var. gigantea (Roth) Arcang. Black bent grass (Engl.)
Agrostis alba var. patula Klett & Richt. Bonnet grass (Engl.)
Agrostis gigantea (Roth) Couch grass (Engl.)
Agrostis stignata var. gigantea (Roth) Schur Creeping bentgrass (Engl.)
Agrostis stolonifera var. gigantea (Roth) Rchb. Fiorin (Engl.)
Agrostis stolonifera subsp. gigantea (Roth) Schübl. & G.Martens Redtop (Engl.)
Agrostis stolonifera var. rothii Heuff. Redtop bent grass (Engl.)
Agrostis vinealis var. gigantea (Roth) Pers. Water bent grass (Engl.)
Agrostis vinealis var. gigantea (Roth) Willd.  
Vilfa gigantea (Roth) P.Beauv.  
Accepted infraspecifics (2)  
Agrostis gigantea subsp. gigantea  
Agrostis gigantea subsp. maeotica (Klokov)Tzvelev  
Some publications list Agrostis gigantea and A. stolinifera as synonyms. POWO lists thems as separate species. Creeping bentgrass as common name is shared by both species.
Agrostis gigantea Roth is an accepted species. KEW: Plants of the World Online

Other vernacular names
CHINESE: Hong zhu gao yun gan.
FRENCH: Agrostide blanche, Agrostide géante, Weiße straußbras.
GERMAN: Fioringras, Riesenstraußgras.
SPANISH: Pasto quila, Agrostide mayor, Agrostide blanca.



Gen info

- Agrostis (bent or bentgrass) is a large and very nearly cosmopolitan genus of plants in the grass family, found in nearly all countries in the world. It has been bred as a GMO creeping bent grass. (5)
- Agrostis gigantea, known as black bent and redtop, is a perennial grass of the Agrostis genus. The species is similar to Agrostis stolonifera, the key difference being the latter has stolons. Sometimes the two are treated as a single species.
- Etymology
: The genus name Agrostis derives from Greek agrostis, meaning "a forage plant, kind of grass", or cf agros, meaning "a field".  The specific name gigantea derives from Latin giganteus, meaning "very large". (3)

Botany
Perennial, rhizomatous; rhizomes tough, scaly, spreading. Culms loosely tufted, ascending to prostrate at base, rooting and branching from lower nodes, up to 130 cm tall. Leaf sheaths smooth or scaberulous; leaf blades linear, flat, 5–30 cm × 3–10 mm, scabrid, apex acuminate; ligule on tillers 1.5–6 mm, as long as or longer than wide, toothed. Panicle oblong or conical in outline, 8–25 cm, contracted at first, open after anthesis; branches 5 or more per node, spreading, very scabrous, bearing branchlets nearly to base, spikelets clustered at the branch apices. Spikelets 2–3 mm, yellowish green or purplish; glumes elliptic-lanceolate, subequal or lower glume slightly longer, scabrid or pilosulous along upper keel and margins, apex acute; callus hairs 0.2–0.4 mm; lemma 2/3–3/4 spikelet length, glabrous, usually awnless, apex obtuse; palea 1/2–3/4 length of lemma. Anthers 1–1.5 mm. Fl. and fr. summer and autumn. (Flora of China)

Distribution
- Naturalized in the Philippines, along trains in open forests. (1)
- In Benguet.
- Not listed at POWO.

- Native to Borneo, Caroline Is., Cook Is., Fiji, Hawaii, Jawa, Lesser Sunda Is., Maluku, Marianas, Marquesas, New Guinea, Niue, Pitcairn Is., Queensland, Samoa, Society Is., Tonga, Tuamotu, Tubuai Is., Vanuatu, Western Australia. (2)
- Reported invasive in some states in the U.S.A. and provinces in Canada.

Constituents
- Study of evaluated Agrostis gigantea for methoxylated flavonoids and volatile constituents.  Aerial parts yielded two methoxylated flavonoids, luteolin 5-methyl ether (1), and cirsilineol (2). GC-MS study yielded volatiel oils of the simple phenolic category, which included: coniferyl alcohol (18.80%) and eugenol (12.19%) in the aerial parts and seeds, respectively. (see study below) (7)

Properties
- Studies suggested cytotoxicity property.


Uses

Edibility
- No reports on human edibility.
Folkloric
- No reported folkloric medicinal use in the Philippines.
Others

- Horticulture: Well-suited for amenity horticulture in the tropics. (2)
- Agroforestry: Introduced in various places as turf, lawn or golf course grass, or for erosion control and revegetation species. Its impact includes displacement of native species in habitats where it is not properly managed. (4)
- Fodder: Use as pasture grass and livestock forage.

Studies
Flavonoids and Volatile Constituents / Cytotoxicity Against Cancer Cell Line:
Study of evaluated methoxylated flavonoids and volatile constituents of Agrostis gigantea. Two isolated flavonoids were investigated for inhibitory activity on 4T1 breast carcinoma cells. The flavonoids exhibited low cytotoxicity against the breast carcinoma cell line with IC50s of 428.24 and 412 µg/mL for luteolin 5-methyl ether and cirsilineol, respectively. (see constituents above) (7)

Availability
- Wild-crafted.

April 2025

                                                 PHOTOS / ILLUSTRATIONS
IMAGE SOURCE: Agrostis gigantea / © John Hilty : 2025: Illinois Wildflowers / Non-commercial use / Click on image or link to go to source page/ Click on image or link to go to source page / GO BOTANY
OTHER IMAGE SOURCE: Illustration: Agrostis gigantea - Inflorescences / © Elizabeth Farnsworth : 2025: New England Wild Flower Society / Non-commercial use / Click on image or link to go to source page / GO BOTANY
OTHER IMAGE SOURCE: Agrostis gigantea - Ligule / Kristian Peters / CC BY-SA 3.0 / Click on image or link to go to source page / Wikipedia
OTHER IMAGE SOURCE: Agrostis gigantea / © Thomas Wrbka Abbott / Some rights reserved / CC BY-NC / Click on image or link to go to source page / iNaturalist

Additional Sources and Suggested Readings
(1)
Poaceae: Agrostis gigantea / Co's Digital Flora of the Philippiines
(2)
Agrostis gigantea / KEW: Plants of the World Online
(3)
Agrostis gigantea / AusGrass
(4)
Agrostis gigantea / ISSG: GLOBAL INVASIVE SPECIES DATABASE
(5)
Agrostis / Wikipedia
(6)
Agrostis gigantea / Wikipedia
(7)
Phytochemical Investigation on Volatile Compositions and Methoxylated Flavonoids of Agrostis giganteaRoth / Mahmoud Rafieian-Kopaei, Azadeh Hamedi, Ebrahim Soleiman Dehkordi et al / Iranian Journal of Pharmaceutical Research,  2020; 19(2): pp 360-370 / DOI: 10.22037/ijpr.2019.15209.12935

DOI: It is not uncommon for links on studies/sources to change. Copying and pasting the information on the search window or using the DOI (if available) will often redirect to the new link page. (Citing and Using a (DOI) Digital Object Identifier)

                                                            List of Understudied Philippine Medicinal Plants
                                          New plant names needed
The compilation now numbers over 1,500 medicinal plants. While I believe there are hundreds more that can be added to the collection, they are becoming more difficult to find. If you have a plant to suggest for inclusion, native or introduced, please email the info: scientific name (most helpful), local plant name (if known), any known folkloric medicinal use, and, if possible, a photo. Your help will be greatly appreciated.

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