Based on Burtts classification and relevant references, the geographical distribution of the subfamily  Cyrtandroideae Endl. emend. Burtt is outlined, distribution  maps of 79 genera are  provided, and some  evolutionary trends of the taxa are inferred. The main points may be summarized as follows:1. The centre  of  distribution The  Cyrtandroideae consists  of four tribes, 79 genera and about 1770 species, widely distributed in tropical and subtropical regions of the Old World, ranging from Guinea eastwards to Nukuhiva Islands and from Western Bulgaria  southwards to Southern Natal, with  only one    species  disjunctly  occurring in  tropical America. According to Takhtajans (1978) regionalization of the world flora, and referring to Goods (1974) and Wus (1979) scheme, the distribution patterns of Cyrtandroideae may be generalized as:  (1) Pantropics, with 3 genera;  (2) Palaeotropics, with 47 genera; and  (3) North Temperate, with 27 genera. Tropical Asia (Indo Malaysia) is the centre of variation and  diversity of the Cyrtandroideae, where the most  primitive taxa, with the chromosome  number of n=8 or n=9, and all of the four tribes exist, and  where more  genera(50) and species (1200 odd) are found than elsewhere. Among the four tribes of the Cyrtandroideae, only two tribes are     distributed west of India. Three European genera with six species, confined to the Mediterranean, belong to one tribe, Didymocarpeae. Of 10 African and     Madagascar genera, 9(7 endemic) belong to Trib. Didymocarpeae, 1 to Trib. Klugieae, and a11 of 168 African and Mada gascar species are not outside both of these regions.

2. Disjunct distribution and dispersal In Trib. Klugieae, two species of  Epithema are found disjunctly in west Africa, and one species of  Rhynchoglossum, R. azureum, is disjunct in tropical  America,  from southern Mexico  to northern Peru. Their closely  allied species  and neighbouring genera are in tropical Asia. Rhynchoglossun azureum has a close  relationship with R. notonianum, which is located  in India and Sri Lanka, so it is hypothesized that Rhyncho glossum existed in north Africa, where there were tropical rain forests  similar to those in Malaysia during the Tertiary. The author noticed that seeds of R. obliquum from tropical areas of southern Yunnan can  still germinate after seven months at normal temperature. Most seeds of this genus are not only long  lived but very tiny (0.3～0.4 mm long), and can be dispersed by wind or birds (epizoochore through the agency of mucus). One or two species of Rhipsalis in Cactaceae was  carried by birds from south America to Madagascar, the Mascarene Islands and Sri  Lanka at an early period. This example  indicates the possibility of this means of distribution. More than  200 species from the volcanic islands of the Polynesian region, including the Hawaiian Islands,all belonging to Cyrtandra, were obviously spread by birds from tropical Asia during an earllier period. The  distribution of two  species of Boea and one species of Cyrtandra in northeast Queensland  shows that some early  taxa of the genera entered Yorke  Peninsua from New Guinea when the sea level was lower during the Quaternary glaciations The modern vicarious distribution patterns of the two subfamilies indicate that the main taxa of the family were produced during the course of the continental drift and the climatic and environmental changes. According to the principle of common origin, the ancestor of Gesneriaceae appeared most probably not later than  the  late  Cretaceous, and  might be traced back to  the Mid Cretaceous.

3. Some problems about evolutionary tendencies In general, the actinomorphic corolla  precedes the  bilabiate one, and the flower with stamens all fertile precedes those with 1 or 3 staminodes (Ivanina, 1965; Wang, 1989、 1992). In some diandrous  genera of  Cyrtandroideae, 4 or 5 fertile stamens may occur exceptionally, and are associated with a more or less regular corolla. The exceptional appearances may possibly be atavistic, not representing the main evolutionary tendencies. In the genus Aeschynanthus, pollen grains of Sect. Haplotrichum and Sect. Diplotrichum, whose corollas usually have indistinct  bilabiate limbs, are comparatively small, but large in sections Microtrichium, Xanthanthos and Aeschynanthus, whose corollas have distinct bilabiate limbs.

4. The relationships of the four tribes he tribes Cyrtandreae, Trichosporeae and Didymocarpeae are closely related (Kvist and Pedersen, 1986). Some terrestrial plants of Trib. Trichosporeae (e.g.Anna and Lysionotus Sect. Didymocarpoides), in which the seeds have subulate appendages at their ends, may represent the intermediate links between tribes Didymocarpeae and Trichosporea.Boeica and Hexatheca form natural links between the tribes Cyrtandreae and Didymocarpeae. The tribes Didymocarpeae and Klugieae probably originated from a common ancestor at an early stage in the evolution of the family.