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FOC | Family List | FOC Vol. 13 | Haloragaceae

2. Myriophyllum Linnaeus, Sp. Pl. 2: 992. 1753.

狐尾藻属 hu wei zao shu

Burshia Rafinesque; Enydria Vellozo.

Herbs perennial, aquatic, submerged or shortly emergent, monoecious or dioecious. Stem soft, few to many branched, rhizomatous. Submerged leaves 3- or 4-whorled, rarely alternate, pectinate, ovate to oblong in outline; segments filiform; emergent leaves smaller, sometimes uppermost ones undivided, reducing to bracts of inflorescence. Inflorescence usually emergent, a terminal spike with flowers 4-whorled, or in axils of emergent leaves. Flowers subtended by a primary bract and 2 bracteoles, sessile, usually 4-merous, minute, lowermost ones female, uppermost ones male, sometimes middle ones bisexual. Male flowers: calyx deeply 2-4-lobed; petals 2-4, boat-shaped, often pink; stamens 2-8, epipetalous. Female and bisexual flowers: calyx tube united with ovary; lobes 4, minute; petals minute, often caducous or absent; ovary (2-)4-celled; style absent; stigmas 4, sessile, recurved, plumose, papillose. Fruit a schizocarp, separating into (2-)4 mericarps. Seed 1 per mericarp.

About 35 species: aquatic or wet habitats worldwide, mostly in Australia; 11 species (one endemic, one introduced) in China.

Myriophyllum has economic importance in the purification of water, as feed for pigs, ducks, and fish, and in polishing wood. The plants are used medicinally to reduce fever and as an antidiarrheal.

Myriophyllum aquaticum (Vellozo) Verdcourt (Enydria aquatica Vellozo) is a commonly cultivated, and nearly naturalized, species in Taiwan, characterized as follows: plants dioecious (only female plants known in China); aerial leaves glaucous or light bluish green; all leaves whorled, never entire, pinnately divided with linear segments; bracteoles subulate with 1(or 2) lateral lobes. This species was possibly introduced by the aquarium trade.

1 Upper flowers alternate   (2)
+ All flowers whorled   (4)
2 (1) Leaves all alternate or pseudowhorled; floral bracts conspicuous.   5 M. dicoccum
+ Leaves whorled; floral bracts inconspicuous   (3)
3 (2) Stamens 8; inflorescence terminal; mericarps abaxially rounded.   1 M. alterniflorum
+ Stamens 4; inflorescence axillary; mericarps abaxially acute.   6 M. tuberculatum
4 (1) Emergent leaves pectinate-pinnatifid   (5)
+ Emergent leaves or at least upper ones undivided, margin entire or serrate   (6)
5 (4) Floral leaves glaucous or light bluish green; turions 6-8 cm.   11 M. oguraense
+ Floral leaves light to dark green; turions 1-3 cm.   2 M. verticillatum
6 (4) Bracts not longer than wide, ovate to orbicular, shorter than or equaling flower   (7)
+ Bracts longer than wide, obovate and subentire to elongate and pinnatisect, extending beyond flower   (8)
7 (6) Mericarps abaxially smooth or finely tuberculate; bracteoles reniform to suborbicular, broader than long.   4 M. sibiricum
+ Mericarps abaxially tuberculate or aculeate; bracteoles ovate, as long as or longer than broad.   3 M. spicatum
8 (6) Plants dioecious; bracts elliptic; male flowers distinctly stalked.   8 M. ussuriense
+ Plants monoecious; bracts lanceolate to spatulate; male flowers not stalked   (9)
9 (8) Bracteoles digitate; sepals triangular.   9 M. tetrandrum
+ Bracteoles ovate; sepals orbicular   (10)
10 (9) Stamens 4; mericarps beaked.   7 M. heterophyllum
+ Stamens 8; mericarps not beaked.   10 M. exasperatum

  • List of lower taxa


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