Elaeagnaceae

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Elaeagnaceae

Distribution

This small family has a typical northern hemisphere range; it is absent from South America, ex-tends in Eurasia only to the Mediterranean and in Southeast Asia to Malesia and NE. Queensland. There are 3 genera of which Elaeagnus occurs throughout the range (20-50 5/7/7.), Shepherdia occurs only in North America (c. 3 spp.), and Hippophaë occurs throughout Eurasia (c. 3 spp.). The habitat is chiefly in steppes and along coasts, but in SE. & E. Asia, Malesia and N. Queens-land Elaeagnus is found as a substage liana in the everwet rain-forest, showing no special preference for seasonal climates.

Taxonomy

About the affinity three opinions prevail. BENTHAM & HOOKER f. (1880) placed the family near the Thymelaeaceae and this position in the Thymelaeales was still upheld by MELCHIOR (1964) and supported by RAO (1974). Most authors, e.g. RENDLE (1952) follow VON WETTSTEIN (1911), who accommodated the family in the Myrtiflorae. CRONQUIST (1981) included it in his Rosidae-order Prôteales, but wondered whether this was not an artificial place. He also pointed out affinities to the Thymelaeaceae which he included in the Rosidae-order Myrtales, but remarked (l.c. 603) that "As a putative member of the Myrtales, the Elaeagnaceae would stand out like a sore thumb on anatomical as well as floral morphological grounds, but an evolutionary relationship via the Thymelaeaceae cannot be ruled out on the basis of present evidence. For the present it will do no harm to retain the Proteaceae and Elaeagnaceae in the same order. When more evidence is available it may become necessary to restore the order Elaeagnales and insert it in a position following the Myrtales."
The latter view was held by TAKHTAJAN (1969), who in 1980, however, placed the Elaeagnales with the Elaeagnaceae as its only family next to the Rhamnales in the Celastranae, which super-order he placed next to the Proteanae, which include the Proteales. The Thymelaeaceae he put in the Malvanae and the Myrtales in the Myrtanae. Such a relationship with the Rhamnales was also proposed by HUTCHINSON (1926, 1959, 1973) and THORNE (1983).
DAHLGREN (1975) recognizes Elaeagnales but does not make a decision about affinity other than those mentioned.
Pollen structure does not lead to an unequivocal opinion about affinity (LEINS, 1967).