THE GENUS MELOCHIA L. (STERCULIACEAE) by Aaron
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THE GENUS MELOCHIA L. (STERCULIACEAE) By Aaron Goldberg History of the Genus Linnaeus validated the name Melochia by including it in the first edition of his Species Plant arum (37). In his Genera Plantarum (38) of the following year under the description of Melochia he cited only Dillenius (9), who had described and illustrated only Melochia cor- chorifolia in the genus Melochia. According to the current Inter- national Code of Botanical Nomenclature (33), it is agreed to associate generic names which appear in Linnaeus' Species Plantarum, edition 1, 1753, with the first subsequent description given under those names in Linnaeus' Genera Plantarum, edition 5, 1754. Therefore, Melochia corchorifolia L. is considered to be the type species of the genus. Melochia is a name altered from the Arabic name of Cor chorus olitorius L., a salad plant in the East, and according to Gray (20) the name was borrowed by the Arabs, through the Syriac, from the Greek word for the mallow. Several genera have been published and subsequently reduced to synonymy under Melochia. In 1777 Houttuyn (27) introduced the name Visenia for his V. umbeUata, a common tree of southeastern Asia and the Pacific Islands. In 1854 Gray (19) expressed the opinion that Visenia could not be generically distinguished from Melochia. In 1895 Schumann (48) gave it its present status as a section of Melochia. In 1787 Medicus (42) introduced the name MolucMa for species with pyramidal fruits—placed in the section Pyramis in this paper. In 1803 Ventenat (64) introduced the name Riedlea, characterized by a 5-valved globular capsule, filaments united in a column, and a calyx subtended by 3 bracts. Riedlea is placed in the section Melochia in this paper. In 1823 Humboldt, Bonpland, and Kunth (28) intro- duced Mougeotia for species with a pentacoccic capsule. DeCandolle (8) reserved the name Melochia for species placed in the section Pyramis in this paper, and used the name Riedleia for Riedlea Vent., Mougeotia H. B. K., and Visenia Houtt. He also established the tribe Hermannie&e, which includes Ilermannia L., Melochiah^ and Waltheria L. Two years later Sprengel (51) used Melochia as did DeCandolle, but substituted Visenia for Riedleia, probably on the basis of priority. 191 192 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM In 1825 St.-Hilaire (46) reported on his rather extensive collections of Melochia in southern Brazil, and gave reasons for not considering Riedlea Vent, generically distinct from Melochia. He mentioned that the flowers are very similar and that, as a rule, other characters being the same, Linnaeus would not divide a genus if the flowers were the same but the fruits different. He did not consider the presence of bracts subtending the calyx a generic character and pointed out that there are intermediate forms in the types of dehiscence of the fruit in Melochia and Riedlea. In 1836 Presl (45) introduced Physodium, and mentioned that it differed from Riedleia in having an inflated, closed calyx, linear anthers, and an acute-angled, stipitate capsule. Bentham and Hooker (3) maintained Melochia and Physodium, but, considering St.-Hilaire's observations and their own, they placed Riedlea in synonymy. Hemsley (25) did not consider Physodium, to be generically distinct from Melochia but followed Bentham and Hooker in maintaining it. In 1854 Triana and Karsten in Triana (58) introduced Anamorpha, and in 1858 Turczaninow (60) introduced Physocodon. Both have since been reduced to Melochia. They contain species now placed in the section Mougeotia. In 1864 Grisebach (22) divided the genus into the sections Eumelo- chia, Riedleia, and Mougeotia. As emended in description, and as changed in nomenclature, in accord with the International Code of Botanical Nomenclature, these sections are maintained in the present paper. Schumann (47), in the next major treatment of the genus, considered all of the genera mentioned above, occurring in Brazil, to be synonyms of Melochia, and he accepted Grisebach's sectional division of the genus. In 1890 Garcke (17) discussed part of the extensive synonymy in the genus. In 1895 Schumann (48), in treating Melochia, added Visenia as a section containing certain species of Asia and the Pacific Islands, and reduced Physodium to synonymy. In 1908 Fries (15) presented his concepts of the taxa in Melochia in South America. He examined and cited specimens from several European herbaria. From time to time species and infraspecific taxa have been described in the genus Melochia and its synonyms. These are considered in the systematic section of this paper. Approximately 379 names and com- binations have been used to describe the types of Melochia. Many are synonyms and many of the descriptions are very inadequate. I have made more than 30,000 observations of characters in the genus. About half of them were measurements under the dissecting micro- GOLDBERG—GENUS MELOCHU 193 scope. Thus, I have supplemented the information in the old descrip- tions. As a result of my studies, I consider 68 taxa to be adequate to describe the entities in the genus. Two new species are described and Physodium is placed in sectional status. Division of the genus into several genera has been based on charac- ters which show a gradual transition between species from section to section as follows: (1) The carpels of some species of the section Mougeotia have an obtusely rounded dorsal surface; in others the carpels are somewhat carinate in the distal half of the fruit and transi- tional to the section Pyramis. (2) In the size of the fruit from the section Mougeotia to the section Pyramis. (3) One type of dehiscence to another occurs between species. (4) The gradual change in degree of accrescence of the calyx, degree of union of the filaments, and length of the stipe. (5) In the size of bracts in all species and in the length of the internode between each of them and between them and the calyx. In addition to the taxonomic treatments already mentioned, several floras and lists have been published in which pertinent Meloehia are presented. Included among the regions treated are Mexico (52), several countries of Central America (25, 53, 54, 55, 56), several of the islands of the West Indies (4, 13, 22, 36, 62), Surinam (61), French Guiana (35), Venezuela (44), Colombia (59), Peru (39), Bolivia (14), tropical West Africa (29), Congo (18), Angola (11), the basin of the Zambesi River (12), Madagascar (1), India (26), Indochina (16, 57), Java (2), the Philippine Islands (43), and Fiji (49). Since the taxa attributed to the various regions by the authors of these floras and by me differ in some cases, I am including tables showing the distribu- tion of the species of Meloehia by countries (pp. 196 and 197). Economic Importance The genus Meloehia has no outstanding economic importance. Some species, such as M. pyramidata, have fine silky fibers, but at present these are used only locally. Some species occur in pasture lands, especially savannas. Gentry mentioned (his specimen no. 943M [MICH]) that burros are very fond of the plant (M. tomenteUa). A few species are weeds in cultivated fields. The plants have a mucilaginous constituent that is used locally as a demulcent in enter- itis due to dysentery. They are also used locally as a salad plant, and for smoking. The flowers are a source of food for honeybees. Meloehia umbeUata (Houtt.) Stapf, a rapidly growing species of southern Asia and the Pacific Islands, is commonly planted as a shade tree in that part of the world. 194 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM Geographic Distribution In America, Mebchia is distributed over more than 5.6 million square miles. It ranges from approximately 33° N. to 33° S. latitude on the east coast, and from approximately 29° N. to 12° S. latitude on the west coast. The distribution of the genus in South and North America is shown in figures 1 and 2, respectively. The coordinates Figure 1.—Distribution of Melockia in South America. of many of the localities of the specimens studied were determined from the "Index to the Map of Hispanic America" (31). GOLDBERG—GENUS MELOCHIA 195 v i'A tih? * :1 V O r & % -tf \) I °i\ r "V \ t r i / S-\ w r*4f>\ si > t i i, Hr \ *#r $ $ V x a 9 V s B I / I1 # i >/ 196 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM Table 1.—Distribution of American Species of Melochia by Countries o a 03 3 Sf 8 a a 3 s a hO o § £ p MELOCHIA d £ p I I O o a 3 c c w 3 3 K Oi A o & PS -< 8 JQ <3 if 'O jG a -a B 8 8 o k TJ d -q 8 1 o 3 a .83 ■a 03 03 08 "3 a) _g a a> £ a "w a E c 2 i p £ d a ifi 8 G s a Q 3 s © 0 *5 *c a cO P § a# 3 o o o e & s O CO W CO u & PQ o ^3 OQ m £ O I Ph PQ to Ah adenodes X anomala X arenosa X X X ar^entina X X beraoulliana X be tonici folia X caracasana X X X clmmaedrys X X X X colombiaoa X corchorlfolia * X X corymbosa crenata X X garrtueri X graminifolla X X X X X X X hassleriana X X hermaonioides X X illicloides X fcemifolia X X X X X lanata X X lonoeolata X X leucantha X lupulins X X X X X X X X X X X inanducata X X X X X X X melissi folia X X X X niollis X X X morongti X X X nodiflora X X X X X X X X X X X X X X X imdifiora X X X X parvifolia X X X X X pilosa x X X X X X X X X X pyramidata X X X X X X X X X X X X X X X X X X X X X X rhodocalyx X savannarmn X simplex X X X X X splendcris X X thymifolia X X X to men UHla X tomentosa X X X X X X X X X X X X tragiifolia X ulmifolia X X X X X X villosa X X X X X X X X X X X X X X X X X X X X X werdermannil X 'Adventlve* Tlie genus occurs in more than 6.7 million square miles of the Old World, from 37° N.