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the 1960s, with an appreciation of significant differences in the embryology and basic chromosome numbers (Dixit 1962; Barlow 1964). Most accounts in the century up to then ranked Viscaceae as a subfamily of Loranthaceae. Later that decade, Kuijt (1968, 1969) removed certain genera from Viscaceae as the Eremolepidaceae, noting differences in the inflorescence structure. That made the morphological separation more clear cut. The Santalaceae have a single whorl of tepals like Viscaceae in this restricted sense, but Loranthaceae have both calyx and corolla, which suggests a relationship nearer to the more basal family Olacaceae, which has the calyx differentiated to varying degrees.

The main differences between the families are indicated in Table 1, adapted from Kuijt (1969) and Calder (1983). The flowers of Viscaceae are generally less than 3 mm across and adapted to pollination by small insects. Except in the primitive genus Ginalloa, the anthers are much modified, opening by one or more small pores. In Loranthaceae the flowers are mostly pollinated by birds and tend to be large and showy. The pollen grains are generally more elaborate and distinctly 3-lobed in Loranthaceae.

Both families have much modified ovaries and peculiar embryology. In Viscaceae there are no ovules and the ovary shows little internal differentiation. A small central placenta, the mamelon, occurs in some genera, but is much reduced or lacking in Viscum. Two to several sporogenous cells differentiate out of the mamelon. The embryo lacks a suspensor, except in Viscum, where it is very short. The arrangement is generally similar in Loranthaceae, but in some primitive genera there are vestiges of what might be interpreted as a vascularised central placenta and four ovarian locules, without, however, any trace of ovules. The embryos are more elaborate than in Viscaceae and often extend up the style. The common features of a marked reduction in the female

Table 1 Major features distinguishing Viscaceae from Loranthaceae, adapted from Kuijt (1969) and Calder (1983).

Loranthaceae Viscaceae

Table 1 Major features distinguishing Viscaceae from Loranthaceae, adapted from Kuijt (1969) and Calder (1983).

Loranthaceae Viscaceae

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