Eastern Redbud (Cercis canadensis L.) and Judas Tree (Cercis siliquastrum L.)
Cercis is a genus of 11 species native to North America, Asia, and Europe. All are large shrubs or small trees under 10 m in height. The genus Cercis is an unusual member of the caesalpinoid subfamily of legumes (Leguminosae sub. Caesalpiniaceae) producin
- PDF / 1,106,538 Bytes
- 10 Pages / 439.37 x 666.142 pts Page_size
- 22 Downloads / 161 Views
GENEVE 1
1 Introduction Cercis is a genus of 11 species native to North America, Asia, and Europe. All are large shrubs or small trees under 10 m in height. The genus Cercis is an unusual member of the caesalpinoid subfamily of legumes (Leguminosae sub. Caesalpiniaceae) producing pea-like, papilionaceous flowers more common to the Fabaceae subfamily. The two most important species are C. canadensis (Eastern redbud) and C. siliquastrum (Judas tree). Both species are similar in appearance, with C. canadensis, produced as a nursery crop in the United States, where it is native, and C. siliquastrum, being commercially important in its natural distribution in Europe (Table 1). Cercis is cultivated as an ornamental landscape tree and for establishment in windbreaks or wildlife habitats. The major distinguishing characteristic of Cercis species is the bright pink, lavender, or white flowers that appear in early spring before the foliage emerges. Cercis can be attractive for 2 to 3 weeks, producing flowers in abundance over the entire tree, including the main trunk and branches (Fig. 1). Various species exhibit a high degree of natural variability for plant morphology as well as tolerance to temperature and drought stress. Several subspecies (varieties) are easily distinguished (Robertson 1976), with cu1tivars being selected for improved landscape use (Table 1). Cercis canadensis has two major disease pests, verticillium wilt (Verticillium sp.) and botryosphaeria canker (Botryosphaeria dothidea). Both disease organisms are fungal and cause die-back of branches. Botryosphaeria canker has become increasingly common and destructive in the Eastern United States and threatens the continued use of C. canadensis as a landscape tree (Vining 1986). Trees in the landscape that are under stress are more susceptible to Botryosphaeria canker. No control measure is available for this pathogen. Conventional propagation of Cercis species is most commonly from seed. The seed exhibits a double dormancy, requiring scarification to allow imbibition of the hard seedcoat followed by cold stratification (Dirr and Heuser 1987). For C. canadensis, seeds can be scarified with concentrated H 2 S04 for 30 min, followed by 40-60 days moist stratification at 5°C for optimum germination. It is common for the nursery industry to sow scarified Cercis seed in outdoor seedbeds in the autumn for spring germination. Dept. of Horticulture and Landscape Architecture, University of Kentucky, Lexington, KY 40546, USA
1
Biotechnology in Agriculture and Forestry, Vol. 16 Trees III (ed. by Y.P.S. Bajaj) © Springer-Verlag Berlin Heidelberg 1991
Eastern Redbud and Judas Tree
143
Fig. IA-C. Morphologic characteristics of Ccrciscalladl'lIsis. A Growth habit ofa sma ll tree.
B Clusters of fully expanded pea-like HoweTS. C Mature leaf shape
Clonal selections of Cercis are difficult to root from stem cuttings and are more commonly attempted from summer T -budding. However, grafting is an expensive alternative method for propagation, with less than 50% budding succ
