Authors: TunyaLee Morisawa, Global Invasive Species Team, The Nature Conservancy
Latin Names: Bupleurum rotundifolium L.
Common Names: Thorow-wax, hare's ear, hound's ear
Seeds of B. rotundifolium are sold for gardening and the plant is used in flower arrangements. A member of the carrot family (Apiaceae), B. rotundifolium possibly originated from Asia.
Most of the information available on this species concerns how to grow it since it is useful for its medicinal constituents. Numerous papers about the secondary compounds (saponins) of Bupleurum falcatum were available and most information below is on this species.
The seeds of B. falcatum often have a low rate of emergence and require a long emergence period. High and constant soil moisture increased the number of emerging seeds and also the time period for emergence. Seed germination rates were highest at 15° C. The germination rate was very low at 25° C and zero germination was observed at 35° C.
Mulches are not recommended because they increase soil moisture and may result in higher germination of seeds. Dry stressing 7-month rosettes and bolting plants of B. falcatum (keeping the plant near the wilting point) demonstrated that the aerial parts of the rosette were reduced but dry stress did not affect the growth of the root in both the rosettes and bolting plants.
If hand pulling, the use of gloves is recommended since the secondary compounds common in the Apiaceae family can irritate skin. Clipping the aerial part of the plant may actually increase the weight of the root. Techniques such as deep ploughing may also increase root weight. Disbudding increased the viability of plants and increased the weight of the root.
A dicamba and 2,4-D mixture may provide control. 2,4-D alone will reduce populations but not kill all plants. Roundup may also be an effective control measure (J. DiTomaso, personal communication). For wild carrot (Daucus carota), glyphosate did provide >74% control when applied at 0.84 kg ai/ha. 2,4-D ester was less reliable when applied at 1.12 kg ai/ha, providing 18% control at one site and 88% at another (Stachler and Kells, 1997).
Choi, B-R; Kang, S-W; Park, K-Y; Kim, D-H. Effects of mulching on emergence and yield of Bupleurum falcatum L. RDA Journal of Agricultural Science Upland & Industrial Crops, v.37, n.2, 1995:106-110.
Hosoda, K; Noguchi, M. Studies on the Cultivation of Bupleurum-Falcatum L. IV. Effects of Disbudding and Picking Flower on the Root Growth and Root Morphology Shoyakugaku Zasshi, v.47, n.1, 1993:39-42
Minami, M; Sugino, M; Hata, K; Hasegawa, C; Ohe, C. Effects of light and temperature on germination rate, development of embryo and change of saikosaponins content during germinating process in the seeds of Bupleurum falcatum. Natural Medicines, v.51, n.1, 1997:40-44.
Minami, M; Sugino, M; Sadaoka, M; Hasegawa, C; Ohe, C; Ashida, K; Ogaki, K. Physiological response and improvement of tolerance to environmental stress in Bupleurum falcatum L. (II) comparison of sensitivities to dry stress between Rosette and bolting plants. Natural Medicines, v.49, n.4, 1995:401-408.
Montazeri, M. Annual broadleaf weeds and their chemical control in dryland wheat in Bakhtaran [Iran]. Iranian Journal of Plant Pathology, n.1-4, 1987:11-12.
Qie, C; Li, G; Song, Q; Suo, J; Sun, D; Sun, Y; Lu, M; Lin, M. Studies on the high yield techniques for Bupleurum falcatum L. Zhongguo Zhongyao Zazhi, v.20, n.2, 1995:76-78, 126.
Stachler, J.M. and Kells, J.J. 1997. Wild carrot (Daucus carota) control in no-tillage cropping systems. Weed Technology v.11, n.3:444-452.