Description: When studying the Gesneriaceae of Guiana (1958) the present author saw a fairly considerable number of misidentified and unnamed specimens some of which proved to belong to undescribed species. Several of the latter are described below. Besides, several of the species he met with, had to be transferred to other genera. New combinations, however, were made only in those cases where the author could examine the type.

Description: The present study was started as a revision of the Gesneriaceae of Suriname (Dutch Guiana). As it proved to be impossible to solve the taxonomic problems on the base of the scanty material from that country only and as the region of the three Guianas inclusive of the Brazilian territory “Amapá” and the Venezuelan “Delta Amacuro” turned out to be a sufficiently natural floristic unit, the author decided to extend his investigations to all Gesneriaceae known from that area. Of those species material of many herbaria was studied in order to obtain a more complete impression of individual variation and geographical distribution. Among the material borrowed for this purpose the author came across misidentified (and unnamed) specimens some of which belonged to undescribed species. When the material was sufficiently ample and well-preserved new descriptions were drawn up; in some cases new combinations (transfers to other genera) were necessary. For the genera Chrysothemis and Napeanthus complete revisions were made, because otherwise it would have been impossible to work out properly the taxonomy of the Guiana species.

Description: For the identification of a flowering plant the first step usually is to discover to which family it belongs. With some experience, the families commonly encountered in one’s area of interest are soon known, but when dealing with specimens from other places, notably those from the vast and rich subtropics and tropics, there is much less certainty. The pertinent literature is often not readily available as it is often found only in expensive, rare or obscure books, or journals, present only in a few specialized institutes. Basically only a few keys to the families of flowering plants of the world have ever been produced, the best known of which at present is Hutchinson’s Key to the families of flowering plants (1973); less well-known are Lemée’s Tableau analytique des genres monocotylédones (1941) (incl. Gymnosperms) and his Tableau analytique des genres dicotylédones (1943), and Hansen and Rahn’s Determination of Angiosperm families by means of a punched-card system (Dansk Bot. Ark. 26, 1969, with additions and corrections in Bot. Tidsskr. 67, 1972, 152-153, and Ibid. 74 1979, 177-178). Of note also are Davies and Cullen’s The identification of flowering plant families, 2nd ed. (1979), which, however, deals only with the families native or cultivated in North Temperate regions, and Joly’s Chaves de identifição das famílias de plantas vasculares que ocorrem no Brasil, 3rd ed. (1977), which may be useful in other tropical areas too. There are a number of excellent keys prepared by an Austrian, Franz Thonner (1863-1928), which deal either with European genera (1901, 1903, 1918), or African ones (1908, 1913, 1915), or with all families of the world (1891, 1895, 1917). Some of these have apparently been completely overlooked, others have been known only to a few, and then sometimes served as a base for keys of their own, thereby again influencing keys by others (see Derived works).

Description: For the identification of a flowering plant the first step usually is to discover to which family it belongs. With some experience, the families commonly encountered in one\xe2\x80\x99s area of interest are soon known, but when dealing with specimens from other places, notably those from the vast and rich subtropics and tropics, there is much less certainty. The pertinent literature is often not readily available as it is often found only in expensive, rare or obscure books, or journals, present only in a few specialized institutes. Basically only a few keys to the families of flowering plants of the world have ever been produced, the best known of which at present is Hutchinson\xe2\x80\x99s Key to the families of flowering plants (1973); less well-known are Lem\xc3\xa9e\xe2\x80\x99s Tableau analytique des genres monocotyl\xc3\xa9dones (1941) (incl. Gymnosperms) and his Tableau analytique des genres dicotyl\xc3\xa9dones (1943), and Hansen and Rahn\xe2\x80\x99s Determination of Angiosperm families by means of a punched-card system (Dansk Bot. Ark. 26, 1969, with additions and corrections in Bot. Tidsskr. 67, 1972, 152-153, and Ibid. 74 1979, 177-178). Of note also are Davies and Cullen\xe2\x80\x99s The identification of flowering plant families, 2nd ed. (1979), which, however, deals only with the families native or cultivated in North Temperate regions, and Joly\xe2\x80\x99s Chaves de identifi\xc3\xa7\xc3\xa3o das fam\xc3\xadlias de plantas vasculares que ocorrem no Brasil, 3rd ed. (1977), which may be useful in other tropical areas too.\nThere are a number of excellent keys prepared by an Austrian, Franz Thonner (1863-1928), which deal either with European genera (1901, 1903, 1918), or African ones (1908, 1913, 1915), or with all families of the world (1891, 1895, 1917). Some of these have apparently been completely overlooked, others have been known only to a few, and then sometimes served as a base for keys of their own, thereby again influencing keys by others (see Derived works).

Description: When studying the Gesneriaceae of Guiana (1958) the present author saw a fairly considerable number of misidentified and unnamed specimens some of which proved to belong to undescribed species. Several of the latter are described below. Besides, several of the species he met with, had to be transferred to other genera. New combinations, however, were made only in those cases where the author could examine the type.

Description: The present study was started as a revision of the Gesneriaceae of Suriname (Dutch Guiana). As it proved to be impossible to solve the taxonomic problems on the base of the scanty material from that country only and as the region of the three Guianas inclusive of the Brazilian territory \xe2\x80\x9cAmap\xc3\xa1\xe2\x80\x9d and the Venezuelan \xe2\x80\x9cDelta Amacuro\xe2\x80\x9d turned out to be a sufficiently natural floristic unit, the author decided to extend his investigations to all Gesneriaceae known from that area.\nOf those species material of many herbaria was studied in order to obtain a more complete impression of individual variation and geographical distribution. Among the material borrowed for this purpose the author came across misidentified (and unnamed) specimens some of which belonged to undescribed species. When the material was sufficiently ample and well-preserved new descriptions were drawn up; in some cases new combinations (transfers to other genera) were necessary. For the genera Chrysothemis and Napeanthus complete revisions were made, because otherwise it would have been impossible to work out properly the taxonomy of the Guiana species.