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Botrychium dissectum Spreng., cut-leaf grape fern, p. 14 
f. dissectum 
f. obliquum (Muhlenb.) Fern. [S, G, M: var. obliquum 
(Muhlenb.) Clute] (Tryon, 1936) 
B. virginianum (L.) Sw., rattlesnake fern, p- 15 
var. virginianum 
OPHIOGLOSSUM, adder’s tongue 
*Ophioglossum crotalophoroides Walter, bulbous adder’s tongue 
omas et al., 1974 
O. engelmannii Prantl, Engeimann’ s adder’s tongue, p. 16 
*O. petiolatum Hook., stalked adder’s tongue (Thomas et al., 
O. vulgatum 
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var. i a (Blake) Farw., northern adder’s tongue 
var. pycnostichum Fern., southern adder’s tongue 
OSMUNDACEAE, royal fern family 
OSMUNDA, royal fern 
Osmunda cinnamomea L., cinnamon fern, p. 20 
var. spectabilis (Willd. yA. Gray 
f. anomala (Farw.) Harris 
f. spectabilis 
POLYPODIACEAE, polypody family 
(see also ADIANT ACEAE, ASPLENIACEAE, 
BLECHNACEAE, DENNSTAED CEAE, 
DRYOPTERIDACEAE, THELYPTERIDACEAE) 
ADIANTUM, ARGYROCHOSMA, CHEILANTHES, 
OTHOLAENA, PELLAEA (see ADIANTACEAE) 
S: Steyermark G: Great Plains Flora M: Mohlenbrock 
