176 TORTULACEiE. 



A. PTERYGONEURON. Stems short. Leaves piliferous. 

 Nerve producing one or two pairs of vertical lamellae on its 

 ventral surface. Peristome wanting or imperfect. 



B. ALOINA. Stems short. Leaves obtuse, rarely mucronate, 

 concave with the margins strongly involute. Nerve very broad, 

 producing abundant granulose threads on its ventral surface. 

 Peristome teeth on a very short basal membrane. 



C. DESMATODON. Short, rarely taller. Leaves soft, 

 ovate, oblong or spathulate ; nerve without distinct appendages. 

 Peristome teeth from a distinct but rarely elongated basal 

 membrane. 



D. SYNTRICHIA. Usually robust and tall. Leaves large, 

 oblong or spathulate, frequently aristate with the narrow excur- 

 rent nerve. Peristome teeth united at base in a long, spirally 

 tessellated tube. 



{Nerve with two or four broad lamellae above 2 

 Nerve without lamellse, with or without granules or filaments 3 



{Capsule oval ; seta short ; cells of lid in straight lines 1. pusilla 

 Capsule cylindric ; cells of lid in spiral lines 2. lamellata 



{Nerve indistinct, broad, hidden above by granular filaments 4 

 Nerve distinct throughout 7 



{Synoicous; capsule elliptic ; Is. very short and obtuse .3. brevirostris 

 Dioicous ; leaves longer and narrower 5 



/Capsule oblique ; Is. acuminate ; spores about 25 p 6. aloides 



^ \ Capsule erect ; Is. usually obtuse ; spores about 15 /u 6 



, ("Capsule more or less elliptic, half covered by calyptra 4. rigida 



\Capsule cylindric, calyptra covering lid only ; Is. incurved'at tip .5. ambigua 



{Ls. more or less distinctly bordered with long, narrow cells 8 

 Leaves without such border 10 



o/Leaves short, under \\ line long ; peristome teeth free 11. marginata 



\ Leaves 2-3 lines long; peristome partly tubular 9 



{Usually short; Is. oblong, scarcely tapering, border variable 14. subulaia 

 Taller and slender ; Is. narrower, tapering, border distinct to apex... 14*. angustata 



/Nerve widened in upper half of leaf, excurrent in a mucro 8. atrovi?-ens 



\Nerve not wider above than below 11 



{Leaves very wide, soft, smooth at back and margin q. cuneifolia 

 Leaves distinctly papillose 12 



/Leaves very obtuse, nerve not (or minutely) excurrent i$.- mutica 



\Nerve distinctly excurrent in a cusp or hair-point 13 



{Leaves ovate-lanceolate, denticulate at apex ; capsule oblique 7. suberecta 

 Leaves oblong or obovate, entire (except ruraliformis ) ; capsule erect .: 14 



f Leaves with spinulose hair-points 15 



|_ Hair-points (or cusps) smooth or nearly so 18 



{Leaves squarrose, with recurved margin (cells 10-12 /*) 16 

 Leaves erecto-patent, margin plane or nearly so above 17 



, /Leaves obtuse, green at apex (except the nerve) 18. ruralis 



\ Ls. narrowed to a hyaline acute apex, confluent with the nerve 18*. ruraliformis 



{Cells small, 6-7 \l, obscure; dioicous if. intermedia 

 Cells ie-12 11, clear ; synoicous; plant tall iq. princeps 



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