Pinguicula ramosa

Michiaki Mabuchi (Japan)

Overview and Distribution

Pinguicula ramosa is endemic to Japan. P. ramosa was discovered at Mt. Koshin-zan (1901 m altitude) by Dr. Manabu Miyoshi in 1890. "Zan", "san", or "yama" are the different Japanese names for "mountain". Koshinso is the Japanese name for plants from this mountain, as "So" means "plant". The distribution of P. ramosa is so limited to Mt. Koshin-san and the neighboring mountains, most of which are in the Nikko mountain region; Tochigi Prefecture. These include Mts. Kesamaru-san, Nantai-zan, Nyoho-zan, Sukai-zan, Nokogiri-yama, Tsuki-yama. Nokogiri-yama is a column between Mt. Koshin-zan and Mt. Sukai-san. Only Mt. Kesamaru is located outside of the Nikko National Park. Collection of plants within Nikko National Park is forbidden by law. Mt. Kesamaru's habitat is important in that it is only one habitat in Gunma Pref. P. ramosa may also be located on Mt. Ozaku-san, which is also out of the Nikko Mountain region. 

Habitat

Pinguicula ramosa grows on almost vertical rock walls at 1500-1700 m elevation. The trail to the habitat is very steep, and not easily accessible. Therefore, there are few good photographic records of P. ramosa. The rock is comprised of weathered, crumbly granite. The soil is slightly damp with periodic fog supplying the majority of water to P. ramosa. The substrate is the porous volcanic rock wall which is always cooled by evaporation via thermal radiation (similar principle as swamp coolers). Most plants are found on the north side of the walls, under half-shaded or sometimes very shaded conditions. Saxifraga fortunei and Primula modesta frequently accompany P. ramosa. P. ramosa starts to grow in April, flowers from June to July, and produces seed in August. Currently, the rock walls of Mt. Koshin-zan are so weathered, they are falling apart. Reasons for this include increased use by mountain climbers and death of the trees on the wall due to acid rain and grazing by deer. The habitat of P. ramosa in Mt. Koshin-zan is now facing a crisis.

Observations of the Plant

P. ramosa is a small rosetted species similar in appearance to P. lusitanica. The leaves are 7-15 mm long and 5-8 mm wide with the edges curling upwards. The upper side of the leaf is covered with glands (traps). Plants which trap many insects tend to produce 2 (sometimes 3 or 4) branched pedicels, the most characteristic aspect of this species. The scape and pedicels are also covered with glands. The flower is light purple to light pink. When it matures the scape bends towards the substrate, allowing the seed to fall onto the surface of the rock wall. The plant forms a small resting bud (3-5 mm diameter) in winter. In habitat the bud is covered with a thin layer of ice, protecting it from the cold (from -20 to -10 degrees C). There are a few variations. A white-flowered form is found in limited numbers at Mt. Koshin-zan while plants at Mt. Tsuki-yama are large with 4 cm-diameter rosettes.