1962 



LEAF'S HEPATICAE OF LATIN AMERICA -PART I 



63 



larger than the leaves, the lateral margins ciliate the segments branched and 

 ciliate, the innermost scries adnate to the perianth, the ciliate segments free. 

 Perianth emergent, cup-form, nearly hemispherical, the mouth large, fringed 

 with many cilia]. Fig. 1, a-j. 



Habitat: not stated. 



ECUADOR: Mount Tungurahua, Spruce (type Manch, iaotype G) 

 PERU: Cuzco: La Convenci6n, Bues 612 b (NY) 



The illustrations of the perianth which were made by Spruce from the origi- 

 nal material suggest that the shoot /sporophyte relationship might be interpreted 

 differently in the light of our present knowledge. Whether a perianth is ac- 

 tually formed can only be determined after material bearing young or older 

 sporophytes is available. 



isotach aceak R. Hatcher, Nova Hedwigia 2: 579. 1960. 



Leafy stems prostrate to ascending or erect, nearly radial to strongly dorsi- 

 ventral in aspect, simple or irregularly branched; branches leafy, ventral-in- 

 tercalary, in the axils of the underleaves or as subfloral innovations in the axils 

 of the female braeteoles. Stem in transverse section with a band of one to three 

 layers of small, thick-walled cells surrounding a medulla of large thin-walled 

 cells. Line of leaf insertion transverse to oblique, the leaves incubous. Leaves 

 bilobed (rarely tri- or quadrilobed) to one-half of their length or less. Under- 

 leaves the size of the leaves or smaller. Male inflorescence terminal becoming 

 intercalary on the stem or branch, the bracts concave, the braeteoles like the 

 underleaves ; antheridia in the axils of the bracts. Female inflorescence terminal 

 on the stem or a branch, the bracts and braeteoles like the leaves and under- 

 leaves, larger, or the innermost series smaller, attached to the perigynium. 

 Shoot/sporophyte relationship a shoot-calyptra surrounded by a thick-walled, 

 hollow, cylindric perigynium with a very short, reduced perianth at the tip. 

 Capsule eylindric-ovoid, the four long valves twisted when open ; wall of three 

 or four layers, the cells of the outer layer large, those of the inner layers smaller, 

 thick-walled; elaters long, tapering at the ends. 



Type genus: Isotachis Mitten. 



The family is monogeneric and the species are limited almost entirely to the 

 Southern Hemisphere. There are 16 species in South America. 



Isotachis Mitten in J. D. Hooker, Bot, Antaret. Voy. 2(2) : 148. 1855.. 



Leafy stems small to robust, pale green or pale rose to dark red, magenta, 

 or brown, prostrate, ascending or becoming erect, in tufts, mats, cushions, or 

 scattered among other bryophytes, simple to irregularly branched below, the 

 branches leafy, of unlimited growth, ventral-intercalary, in the axils of under- 

 leaves or as subfloral innovations from the female braeteoles ; stem in transverse 

 section with a medulla of thin-walled cells surrounded by one to three layers 

 of smaller, usually thick-walled cortical cells. Rhizoids when present colorless, 

 in fascicles from the basal part of the underleaves. Line of leaf insertion oblique, 

 the leaves incubous. Leaves ovate, ovate-truncate, oval, or orbicular in outline, 

 symmetric or asymmetric, bifid to one-half of their length into two equal or 

 subequal triangular, entire to coarsely dentate or ciliate segments; cells of the 

 lamina irregularly rectangular in outline, or quadrate near the margins and in 

 the segments, the walls thin to more or less thickened, with or without trigones 

 and intermediate thickening, the cuticle smooth to striolate-papillose. Under- 



