Trifolium alexandrinum

Cultivation Details

Trifolium alexandrinum is a plant of the Mediterranean to subtropical zone. It grows best in areas where annual daytime temperatures are within the range 16 - 27°c, but can tolerate 3 - 35°c^[1]. When dormant, the plant can survive temperatures down to about -8°c, but young growth can be severely damaged at -2°c^[1]. It prefers a mean annual rainfall in the range 450 - 900mm, but tolerates 300 - 1,700mm^[1]. 25% of a stand of the cultivar 'Sacramento' has been reported to have survived temperatures falling to -15°. However, most cultivars only tolerate light frosts^[1]. Requires a sunny position^[1]. Succeeds in a range of well-drained soils, preferring a heavy loam^{[2, 1]}. Plants are relatively tolerant of saline soils^[1]. Prefers a pH in the range 6.5 - 7, tolerating 4.9 - 7.5^[1]. The plant probably arose through cultivation from a wild species in Syria. It is grown especially in Egypt, but also in northern India and in warm temperate climates of southern Europe and as a non-seeding annual crop in temperate areas with hot summers^{[3, 2]}. Especially in Egypt there are hundreds of local races which could be classified into the multi-cut group, profusely basally branched and late-flowering and the single-cut group, sparsely branched and early; both had been given varietal rank^[3]. Domestication took place presumably in Syria, it was known from Egypt by the 6th century, but untill the late 19th century it was grown only in its traditional eastern Mediterranean area^[3]. This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby^[4].