Sedum
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HAKONENSE Makino, 1901

 

Synonyms :

Sedum habonense  Makino (s.a.)

Sedum rupifragum  Koidzumi (1938) / Sedum hakonense var. rupifragum  (Koidzumi) Ohwi (1965)

 

Distribution : China (Northern Guangdong), Japan (Southern Hondo, Honshu), in cool-temperate mountain forests, on rocks or tree trunks, 1600 - 1700 m.

 

 

 

Description (according to IHSP, 2003) :

 

Perennial herbs with rather stout basally much branched suberect stems, 6 - 8 cm tall.

 

Leaves alternate, narrowly oblanceolate, somewhat rounded, fleshy, 5 - 25 mm.

 

Inflorescences : Flowering branches erect to ascending, loosely tufted, decumbent at the base, 6 - 10 cm tall, inflorescences rather lax many-flowered cymes with 3 sometimes forked cincinni, bracts leaf-like, 4 - 10 mm.

 

FIowers 4- (rarely 5-) merous, sessile, sepals broadly sessile, unequal, triangular, obtuse, nodulate near the tip, 1-veined, 0,5 - 1 mm, petals ovate-lanceolate to semi-oblong, acute, shortly mucronate, yellow, 4 – 4,5 mm.

 

Cytology : 2n = 136 (as S. rupifragum)

 

Sedum rupifragum has 4- or 5-merous flowers. Ohwi (1965: 35) included it in S. hakonense as variety, while Ohba (2001: 27-28) recognized it as a separate species.

 

 

 

Ray Stephenson (Sedum, Cultivated Stonecrops, 1994, p 159 & p 169) :

 

In 1994, R. Stephenson considered Sedum hakonense and S.rupifragum as distinct species. His comment Nov. 2012 : “At the time I wrote the book I had one of each and they looked different. I still have no field experience of either nor am I likely to gain any. If Henk came to the conclusion they were different forms of the same species then I cannot argue. S. rupifragum was much hardier for me but if it is a widespread species then this isn't surprising.”

 

Sedum hakonense (p 159) :

 

Common name : Matsu-no-ha-mannengusa

 

Sedum hakonense is a fairly typical Japanese sedum resembling S. rupifragum and others. It is a creeping, then ascending plant, much branched from the base, with linear, loosely tufted, scattered leaves that are more succulent than those of S. lineare. Plants are usually no more than 5 cm (2 in) tall, but stems are often twice this length. Many 4-partite, pale yellow, sessile flowers of late summer are carried on a 3-branched cyme. The species is exceptionally rare in cultivation, even in Japan.

 

Habitat : This stonecrop is indigenous to mountains of southern Honshu, Japan.

 

Main points of distinction : Leaves are not particularly distinct, but 4-partite flowers are rare in this group. Tiny sepals are unequal and fairly deltoid. Turgid fruit are pronounced kyphocarpic.

 

Variation : Unable to comment.

 

Horticulture : Sedum hakonense is almost hardy. If you manage to acquire a piece to pro-pogate, give plenty of cuttings away so you can beg one back if you lose your plant.

 

Sedum rupifragum (p 169)


Common name : Ō-me-no-mannegusa

 

Usually an erect, tufted stonecrop, Sedum rupifragum grows to about 8 cm (3 in) high. Stems, particularly in winter, are topped with loose rosettes of bright, flat, quite narrow, elliptic, patent leaves. Leaves have a median groove on upper surfaces and are deflexed towards their tips. In summer, rosettes are less well-defined as stems elongate, and leaves are present on the upper two-thirds. Flowers in early summer are on 3-branched inflorescences.

 

Habitat : This species is native to mountains of southern Honshu.

 

Main points of distinction : Three features are the best means of identification: rosettes in winter are very distinct, the neat upright nature of short stems, and the shape of leaves. Small, unequal, deltoid sepals are neither free nor spurred. n = 68.

 

Variation : Due to the limited range of this species in the wild, little variation is expected.

 

Horticulture : The species is a very neat, slow to propagate, and almost always hardy in Mid Northumberland. It makes an excellent alpine plant for a shallow pan, but is equally beautiful in a rock garden, a raised bed, or a stone trough. It is one of the most refined species in the Far East group, but its diminutive nature necessitates that it be grown on an elevated site.



Photo Ray Stephenson



Photos Éric Barbier



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