Podostemum uruguayense Warming ("Podostemon uruguayensis" ), Vidensk. Selsk. Skr., ser. 6, 9(2): 133. 1899.-TYPE: URUGUAY. Sal to: Salto Grande, 15 Dec 1892, Osten 2904 (lectotype, here designated: C!; isolectotypes: B! C! G! L-3 sheets!).
Podostemum dentatum P. Royen, Acta Bot. Neerl. 3: 241, 259. 1954.- TYPE: BRAZIL. Santa Catarina: Rio Tubarao, on Pedras Grandes, Ule 1876 (holotype: P; iso types: L! US!). Plant description: Roots 0.3- 8 (1.2) mm wide. Stems monomorphic, arising 1-15.4 (4) mm apart along root, 0.2-70 (4) mm long. Leaves sessile or petiolate, upright, arising in a ca. 130° distichous arrangement (making stems appear dorsiventral), simple (usually) to 1-4 times dichotomously divided, 0.1-34 (5.1) mm long, 0.2-1.5 (0.4) mm wide; blade of simple leaves and ultimate division of compound leaves linear to spatulate; leaf divisions arising in a 2-dimensional manner; ultimate divisions 0.5-15 (4.1) mm long, 0.2-1.5 (0.4) mm wide, flattened in cross section, apices blunt, rounded, acute or apiculate, with a faint central vein or central vein absent; petioles 2.3-21.2 (8.3) mm long, oval to flattened in cross section; leaf bases asymmetrical, equal in width to the blade to markedly wider, flexible or rigid, obliquely attached to stem; stipules composed of a single, asymmetrically placed marginal or submarginal lobe on one side of leaf base, 0.05-1.6 (0.5) mm long, 0.05-1.4 (0.3) mm wide, entire or slightly emarginate, flattened, flexible or thickened and rigid, persistent and hardened on older portions of stems. Flowers 1-10 (1) per stem; spathella 2-5 (3) mm long, 0.8-1.8 (1.3) mm wide, smooth to minutely papillate, apex rounded or with a nipple; tepals 3, linear or awl-shaped, straight or curved, apex acute; lateral tepals 0.5- 1.9 (1.1) mm long; andropodial tepal 0.1-1.3 (0.7) mm long, often absent; andropodium 0.1- 3 (1.2) mm long prior to anthesis, during anthesis to 0.8- 3 (2) mm; stamens 2; filaments 0.1-0 .8 (0.4) mm long prior to anthesis, during anthesis to 0.4-1.5 (1) mm; anthers 0.3- 1.5 (0.9) mm long, 0.3-0 .9 (0.6) mm wide; pollen dyads 30-40 (33) µm long, 20-25 (20) µm wide; ovary 0.8-2.3 (1.6) mm long, 0.6-1.8 (1.2) mm wide; stigmas entire, 0.2-0 .9 (0.5) mm long prior to anthesis, during anthesis to 0.6- 1.2 (0.9) mm; pedicels 0.4-2.5 (0.7) mm long prior to anthesis, during anthesis to 1.6-6.4 (4) mm. Capsules 1-2.7 (1.8) mm long, 0.9-1.9 (1.3) mm wide; 6 ribbed (3 per valve), suture margins also rib-like; pedicels in fruit 1.7-7 (3.8) mm long; seeds 0-105 (35) per capsule, 0.2-0.5 (0.4) mm long, 0.1-0.4 (0.3) mm wide.
Distribution. Argentina (Corrientes, Entre Rios, and Misiones), Brazil (Rio Grande do Sul, Santa Catarina, Sao Paulo), and Uruguay (region of Salto Grande in the Uruguay River); locally abundant or rare, forming dense growth on horizontal to vertical rock surfaces; 20-878 m.
Podostemum muelleri can occur alone or with P. comatum, P. distichum, P. irgangii, P. rutifolium subsp. rutifolium, Tristicha trifaria, and at least one species of Apinagia.
REPRESENTATIVE SPECIMENS. Argentina. CORRIENTES: arroyo Garabi, Estancia Garruchos, Depto. Santo Tome, Pedersen 9236 (C, L, S, US).-ENTRE Rtos: Rfo Uruguay, Saito Grande, Nicora 6292 (U).-MISIONES: arroyo Tabay, Saito de! Tabay, Depto. San Ignacio, Tur et al. 2108 (LP, MEXU, WCSU); Saito Tabay, Tur 1305 (LP); Saito Tabay, Ldor. Gral. San Martin, Tur & Guaglianone 2046 (LP); arroyo Cunapiru, Saito Encantado, Depto. Ldor. Gral. San Martin, Tur & Guaglianone 1959 (LP); arroyo Paranay Guazu, Tur 1134 (LP); arroyo Piray Guazu, Dpto. San Pedro, Tur et al. 2141 (LP, MEXU, WCSU); arroyo Parafso, road to Mocona, 34 km from Soberbio, Saito Mocona, Tur et al. 2147 (LP, MEXU, WCSU); arroyo Piray Mina, Depto. El Dorado, Tur et al. 2119 (LP, MEXU, WCSU); salto de! arroyo Capiovi, Libertador General San Martin, Tur et al. 2111 (LP, MEXU, WCSU). Brazil. RIO GRANDE DO SUL: arroyo Alegre, Neu-Wurtemberg, Bommueller 737 (L); arroyo Quilombo, Candelaria Co., Philbrick et al. 5008-5009 (MEXU, WCSU); Rio de Vacacai, below dam called Barragem Corsan, Philbrick et al. 5010 (ICN, MEXU, WCSU); large river that drains into Rio Jaguari, near Ernesto Alvos, Philbrick et al.5038, 5039 (ICN, MEXU, WCSU); Rio Concei1rao, 11 km W of Ijui, Philbrick et al. 5050, 5052 (ICN, MEXU, WCSU); small river running under road (BR-386), 29 km NW of Soledade, Philbrick et al. 5056 (ICN, MEXU, WCSU); Rio Fao, along BR-386, near Pouso Novo, Philbrick et al. 5082-5085 (ICN, MEXU, WCSU); Rio Butia, 25 km W of Soledade, Philbrick et al. 5062 (ICN, MEXU, WCSU); small river passing under road to Teinhas, 3 km SE of Cambara do Sul, Philbrick et al. 5119 (ICN, MEXU, WCSU); Rio Moraes, 16 km S of Born Jesus, Philbrick et al. 5143 (ICN, MEXU, WCSU); Rio das Antas, ca. 100 m down stream of confluence with Rio Moraes, Philbrick et al. 5147, 5148 (ICN, MEXU, WCSU); Rio Pelotas (border of states of Rio Grande do Sul and Santa Catarina), 41 km N of Vacaria, Philbrick et al. 5158 (ICN, MEXU, WCSU); Rio Forqueta, Cascata Garapia, Barra do Ouro, Philbrick et al. 5189-5191 (ICN, MEXU, WCSU); ar royo Chuvisquiro, large waterfall, ca. 4 km above Riozinho, Philbrick et al. 5194B, 5195 [mixed with P. distichum], 5195B, 5199, 5200, 5204 (ICN, MEXU, WCSU); arroyo Teixeira Soares, Marcelino Ramos, Philbrick et al. 5315, 5316 (ICN, MEXU, WCSU); Rio Suzana, Gaurama, Philbrick et al. 5354-5358 (ICN, MEXU, WCSU); arroyo do Conouto, Riozinho, Philbrick et al. 5208 (ICN, MEXU, WCSU); Rio Uruguay, Saito do Yu cuma National Park, I km N of Derrubadas, Philbrick et al. 5209-5214 (ICN, MEXU, WCSU); Rio Turvo, Lara, Philbrick et al. 5232-5241 (ICN, MEXU, WCSU); Rio Burica, Cascata, Philbrick et al. 5249-5253, 5255-5260 (ICN, MEXU, WCSU); Rio Vila Lageado Grande, Vila Lageado Grande, Philbrick et al. 5261-5264 (ICN, MEXU, WCSU).-SANTA CATARINA: Rio lguape, Iporanga, Glaziou 6359 (B, C, G, K, P); Rio Itajahy, F. Mu ller.(ex Herb. Schwacke 5055) (C); Blumenau, G. Muller s.n. (B); Rio Pelotas River, 41 km N of Vacaria, Philbrick et al.5159 (ICN, MEXU, WCSU); Saito Pombinha, Pouso Redondo, Philbrick et al. 5163-5168 (ICN, MEXU, WCSU); Rio Tafona, ca. 16 km W of center of Blumenau, Philbrick et al. 5181, 5182 (ICN, MEXU, WCSU); Rio Vacutinga, Conc6rdia, Philbrick et al. 5388-5390 (ICN, MEXU, WCSU); Rio Engano, Conc6rdia, Philbrick et al. 5398, 5399 (ICN, MEXU, WCSU); Rio Irani, Seara, Philbrick et al. 5402, 5403, 5405 (ICN, MEXU, WCSU); Rio Chapec6, Quedad do Rio Chapec6, 5 km W of Abelardo Luz, Philbrick et al. 5461, 5462 (ICN, MEXU, WCSU); Rio Apiuna, Apiuna, Philbrick et al. 5498, 5499, 5503, 5504, 5506 (ICN, MEXU, WCSU); Rio Itajai-A u (Rio ltajai Oeste), lbirama, Philbrick et al. 5494-5496 (ICN, MEXU, WCSU); Rio ltajai, 15-20 km upstream (W) of center of Blumenau, Philbrick et al. 5508-5511 (ICN, MEXU, WCSU); Rio Ita jai, border of lpiuna and lbirama, Philbrick et al. 5517-5520 (ICN, MEXU, WCSU); Rio ltajai del Norte, lbi rama, Philbrick et al. 5524-5527 (ICN, MEXU, WCSU); confluence of Rio ltajai and Rio Itajai del Norte, lbirama, Philbrick et al. 5537, 5538 (ICN, MEXU, WCSU); Itapiranga, Rambo 60293 (B); Rio Uruguai, Itapi ranga, Rambo s.n. (US); Garcia brook, Blumenau, Schenck 186 (U); Blumenau, Schenck 288,293 (C); Itajahy, near Blumenau, Schenck 331 (C); Rio ltajahy, Blumenau, Schwacke 5010 (C); Rio Garcia, Blumenau, Schwacke 5012 (C); Rio Itajahy, Blumenau, Schwacke 5013 (C, L); ltajahy River, Blumenau, Ule 862 (P, US, L); Rio Tubariio, Ule 1876 (L, US).-SA.0 PAULO: Rio Iguape, [collector unknown] 2415 (C); Rio Iguape, Iporanga, Glaziou 86 (C), 279 (G), 883 (G), 889 (G), 2133 (G), Glaziou 3134 (G, P), 3136 (G), Glaziou s.n. (G), Lofgou s.n. (C), Puiggari 852 (C, L), 889 (C); Rio Piracicaba, Glaziou 19816 (C, K, L), Glaziou 19876 (C); Rio Ribeira de lguape, Bauer 13054 (U); without locality, Glaziou 15443 (C, K, P), 15444 (including 15444c) (C), 16358 (C, K, L, P). Uruguay. SALTO: Saito Grande, Concordia, Cabrera 10854 (LP); Rio Uruguay, Catarata Saito Grande, Felippone 5255 (L); Saito Grande, untergetaucht an Felsen im Wasserfalle, Osten 1904 (C); Saito Grande, Osten 2904/2905 (C), 2905 (C); Saito Grande, Tur 1867 (LP).
Podostemum muelleri is characterized by its dorsiventral stem, asymmetrically placed single stipule, ca. 130° distichous leaf arrangement, oblique leaf attachment to the stem, and ribbed capsules. Jager-Ziim's (2002) account of the development of the leaves of P. weddelliana (as Crenias weddelliana) seems to correspond to the sequence in P. muelleri. The stipule occurs on the margin of the leaf base early in development, but can become submarginal later.
Podostemum muelleri is a morphologically variable species. Much variation is associated with plant size. Plants in some populations are small and possess leaves in which the leaf base is barely wider than the blade. In these populations the leaf base and stipule are thin and flexible, and the stipule lies flat against the leaf base. Other populations, com posed of robust plants, possess thickened, rigid leaf bases and stipules; in these the thick ened stipules project from the leaf bases at a marked angle. It remains unknown what environmental conditions influence size.
We interpret three species recognized by Royen (1954) as environmental forms of P. muelleri (P. dentatum, P. galvone, and P. uruguayense). Royen (1954) described P. dentatum as possessing a tooth-like appendage along the margin of the expanded leaf bases of apical leaves opposite the location of the stipule. Examination of specimens from the type collection revealed considerable variation for this character, i.e., only about 50% of the leaves had the extra tooth. Plants in some other populations also have the extra tooth, where its frequency ranged from< 5% to about 60%. No populations were documented in which the plants were fixed for this character.
We interpret P. galvone as an environmental variant of P. muelleri (the "galvone form"). Leaf blades in the galvone-form fail to develop fully, i.e., remain 0.2-2 mm long. These diminutive blades are rounded apically and somewhat rigid. Interestingly, plants in occasional populations of other Podostemum taxa, especially P. rutifolium subsp. rutifolium, also can produce diminutive leaves that look similar to those of the galvone-form of P. muelleri.
We conclude that what others have recognized as P. uruguayense represents robust plants with thick, rigid leaf bases and stipules of P. muelleri that represent one extreme (large) of a continuum of plant size.
Podostemum muelleri was described by Warming (1889) based on materials from Santa Catarina, Brazil. Royen (1954, p. 243) incorrectly lists the publication date of the protologue as 1899. Seven collections are listed with Warming's protologue (Warming 1889, p. 455, 480), thus necessitating selection of a lectotype. Royen (1954, p. 243) listed the type (i.e., lectotype) of P. muelleri as Mueller s.n. in B. It is apparent that Royen was referring to the only specimen of P. muelleri in B with "Mueller" indicated as the collector, although the collector is noted as "Guil. Mueller" (i.e., Wilhelm Muller, the brother of Fritz Muller); Royen's annotation label is on the specimen, but does not indicate "type." Yet, in the protologue Warming (1889) listed Fritz Mueller as the collector of one of the syntypes. It is not possible to determine whether the Muller collection in B is from the same gathering as the Fritz Muller collection to which Warming (1889, p. 480) refers. Thus, we set aside Royen's (1954) choice of lectotype for P. muelleri and here designate a new lectotype. Specimens representing all but one (Schenck 186) of the collections in dicated by Warming (1889, pp. 445 and 480) are located in C; other herbaria (B, K, L) have material of only one or two of these collections. We have chosen the pressed specimen of Glaziou 15444C (specimen 1561, 6) in C as the lectotype. This specimen has com plete leaves and shows the vegetative features that Warming used to describe P. muelleri. In addition, in C there is one jar of spirit material of Glaziou 15444C Gar no. 3205), which is an isolectotype.
Warming (1899, p. 133) listed two syntype collections, Osten 2904 and 2901 from Uruguay (Dept. Salto, "Salto Grande," 15 Dec 1892), in his protologue of "Podostemon uruguayensis." We could not locate any material of Osten 2901. We examined several specimens of Osten 2904 from B, C-3 sheets, G, and L-3 sheets. Royen (1954, p. 242) listed the type (i.e., lectotype) as Osten 2904 housed in C; however, there are three spec imens of Osten 2904 in C. We select the specimen numbered 15611• 5 as the lectotype. A single envelope is attached to this sheet, which contains two fragment packets. On one fragment packet is written Osten 2904; this contains the lectotype. The other fragment packet is labeled Osten 2905, which is of no nomenclatural significance. A second sheet in C (15611• 6) has fragmentary material of Osten 2904 and is an isolectotype. Isolectotypes are also located in B, G, and L-3 sheets. The three isolectotypes in L have typed labels on which are indicated either "TYPUS" or "TYPE." Royen (1954) did not note the presence of these specimens in L. It is likely that this material represents fragments removed from specimens in C, although it is not clear from which specimen.