Juniperus taxifolia / Bonin Islands juniper

Juniperus taxifolia, as described in 1838 by William Jackson Hooker (1785–1865) and George Arnott Walker Arnott (1799–1868), in The Botany of Captain Beechey's Voyage, is commonly known as Bonin Islands or Ogasawa juniper; as well as シマムロ (Shimamuro) in the Japanese language. The species name, Latin for "yew-leafed" describes the much flatter, broader needles with 2 well-separated stomatal bands, especially compared with the similar species, Juniperus thunbergii (Ryuku juniper) and J. conferta (Japanese shore juniper).

Description. Bonin Islands juniper is an evergreen coniferous shrub that grows to mature heights of 3 to 10 feet (1 - 3 m), rarely a small tree to 40 feet (13 m tall), with a trunk up to 6 inches (15 cm) in diameter, measured at breast height. The crown is low and irregular and branching is generally spreading, contorted, and sometimes rising. This species is dioecious, with separate male and female plants.

  • Bark is brown when young, ageing to grayish brown. It is fibrous and peeling into thin strips.
  • Leaves are needle-like, in whorls of three, colored light green, measuring 0.28 to 0.56 inch (7 - 14 mm) long and 0.04 to 0.06 inch (1 - 1.5 mm) broad, with a double white stomatal band (split by a green midrib) on the inner surface.
  • Pollen cones are borne singly in leaf axils; they are yellow in color, with an obovoid shape, measuring 0.2 inch (5 mm) long.
  • Seed cones are berry-like, green in color when young, ripening in 18 months after pollination to reddish-brown with a variable light waxy coating; they are spherical, measuring 0.32 to 0.4 inch (8 - 10 mm) in diameter, and have 6 or 9 fused scales in 2 or 3 whorls of three; the three larger scales each bearing single seed.
  • Seeds are are borne 3 per berry, and light brown in color with a pale attachment scar extending halfway up the side. Individual seeds measure 0.16 to 0.2 inch (4 - 5 mm) long. They are dispersed when birds eat the cones, digesting the fleshy scales and passing the hard seeds in their droppings.
the Boonin Islands are southeast of the main Japanese islands.
the Boonin Islands are southeast of the main Japanese islands.

Distribution. This species is native to southeastern Japan — the Ogasawara Islands, growing from near sea level to 1,000 feet (300 m) elevation, in sunny stony places.

Hardy to USDA Zone 9 — cold hardiness limit between 20° and 30°F (-6.6° and -1.1°C).

Attribution from: Aljos Farjon; A monograph of Cupressaceae and Sciadopitys; ©2005, Royal Botanic Gardens, Kew, United Kingdom.

Juniperus taxifolia when young is often seen as a ground cover.
Photo by Evergreen Growers, Inc., Australia
Juniperus taxifolia — a closeup of foliage and pollen cones.
Photo by Shiro TSUYUZAKI
Juniperus taxifolia — detail of branch structure.
Photo by Shiro TSUYUZAKI
Juniperus taxifolia — a closeup of foliage and seed cones.
Photo by Shiro TSUYUZAKI

Comments