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Flora of Taiwan | Family List | Onagraceae

Circaea L.



Circaea alpina subsp. imaicola

Credit: HAST

Perennial rhizomatous herbs, often forming large colonies. Leaves petiolate, opposite, becoming alternate and bract-like in inflorescence. Inflorescence terminal on main stem and at tips of short axillary branches, a simple or branched raceme. Flowers white or pink, 2-merous, with a floral tube; ovary uni- or bilocular; ovules 1 per locule; sepals and petals alternate, stamens opposite sepals; petals notched at apex; nectary surrounding base of style, wholly within floral tube or elongated and projecting as a fleshy, cylindrical or ring-like disc; style equalling or longer than stamens, stigma 2-lobed. Fruit an indehiscent capsule, covered with stiff uncinate hairs; with or without conspicuous rows of corky tissue. Seeds smooth, fusiform or broadly clavoid to slenderly ovoid, adhering firmly to inner ovary wall. n=11.

A genus of 7 species and an additional 7 subspecies in temperate and boreal forests of the northern hemisphere from near sea level to 5,000 m, and from 10 to 70 N. Lat; 4 species are in Taiwan. Interspecific hybrids are common and often abundant in naturally disturbed habitats in North America, Europe and Japan, but are unknown from Taiwan.

Flowers, mature fruit, and carefully collected rhizomes are highly desirable to facilitate identification. The nature of the nectary is most easily determined in living plants.

Boufford, D. E. 1983 ("1982"). The systematics and evolution of Circaea (Onagraceae). Ann. Missouri Bot. Gard. 69: 804-994.


1 Ovaries and fruit unilocular; rhizomes terminated by tubers; flowers clustered on erect or scending pedicels at anthesis.   subsp. imaicola
+ Ovaries and fruit bilocular; rhizomes without tubers; flowers separate, pedicels spreading at anthesis.   (2)
2 (1) Nectary wholly included within floral tube, not projecting as a cylindrical or ring-like disc beyond opening of floral tube.   (3)
+ Nectary exserted beyond floral tube, projecting as a cylindrical or ringlike fleshy disc above opening of floral tube.   (4)
3 (2) Axis of inflorescence with glandular and nonglandular hairs; fruit obliquely thick lenticular to flattened pyriform, obliquely rounded to pedicel.   Circaea cordata
+ Axis of inflorescence glabrous or with only glandular hairs; fruit obovoid to pyriform, not at all or only slightly flattened, tapering smoothly to pedicel.   Circaea glabrescens
4 (2) Petals obovate to depressed broadly obovate, notched 1/4 or more their length; axis of nflorescence and pedicels commonly pubescent; fruit with prominently thickened ribs, these separated by conspicuous grooves (sulci).   Circaea mollis
+ Petals obtrullate, notched 1/5 or less their length; axis of inflorescence and pedicels glabrous; fruit without prominently thickened ribs and deep grooves.   Circaea erubescens

Lower Taxa

Related Synonym(s):


Related Objects  

Flora of China  
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