Filicineae, Gymnospermae and Other Monocots Excluding Cyperaceae: Ferns, Conifers, and Other Monocots Excluding Sedges

Descriptions and Illustrations

Descriptions and Illustrations 1. AZOLLACEAE—MOSQUITO FERN FAMILY Azolla is the only genus worldwide. 1. Azolla Lam.—Mosquito Fern Plants aquatic, floating, with slender roots; stems usually prostrate, glabrous; leaves with minute hairs on upper surface of upper lobe; sporocarps paired; microspores in masses, covered by arrowlike barbs (glochidia); megaspores globose, containing 3 floats and a blue-green algal colony. Azolla consists of seven species in the tropics and temperate parts of the world. The majority of plants in a colony at a given time do not bear sporocarps. It has been traditional since 1944 to use the number of septae in the glochidia of the microspores to identify the species, but this character is not reliable. Within cavities of the upper leaf lobe are colonies of the blue-green alga Anabaena azollae, which is a nitrogen-fixing organism. As a result, Azolla is often used as an agricultural fertilizer or mixed with livestock food as a nutritional supplement. 1. Plants dark green to reddish; stems 0.5–1.0 cm long; megaspores densely covered with tangled hairs .................................................................................................. 1. A. caroliniana 1. Plants green or blue-green to reddish; stems 1.0–1.5 cm long; megaspores sparsely covered with tangled hairs ............................................................................................ 2. A. mexicana 1. Azolla caroliniana Willd. Sp. Pl. 5(1):541. 1810. Fig. 1. Plants dark green to reddish, free-floating or occasionally forming mats; stems 0.5–1.0 cm long; upper lobe of leaf about 0.5 mm long; megaspores densely covered with tangled hairs. Stagnant or slow-moving water in ponds, lakes, and streams. IA, IL, IN, KS, KY, MO, NE, OH (OBL). Mosquito fern. 2. Azolla mexicana C. Presl, Abh. Konigl. Bohm. Ges. Wiss., ser. 5, 3:150. 1845. Fig. 1. Plants green, blue-green, to reddish, free-floating or occasionally forming mats; stems 1.0–1.5 cm long; upper lobe of leaf about 0.7 mm long or longer; megaspores sparsely covered by a few short filaments. Stagnant or slow-moving water in ponds, lakes, and streams. IA, IL, KS, MO, NE (OBL). Mosquito fern. 2. BLECHNACEAE—CHAIN-FERN FAMILY Leaves monomorphic or dimorphic; blades pinnatifid to bipinnate; veins of leaves usually united; sori elongated along vein; indusia opening from the side; spores reniform. 1 1. Azolla caroliniana b. Microsporocarp. d. Microsporocarp. (Mosquito fern). c. Glochidium. e. Glochidium. a. Habit. Azolla mexicana. 2 This family consists of ten genera, with only Woodwardia occurring in the central Midwest. There are approximately 250 species in the family worldwide. 1. Woodwardia Sm.—Chain-fern Stems long-creeping, with brown scales; leaves monomorphic or dimorphic, the sterile ones pinnatifid or pinnate; rachis scaly; sori in chainlike rows along the veins. Of the fourteen species that comprise this genus, two are found in wetlands in the central Midwest. Despite the fact that both species are placed in the same genus, they are quite different in that one species is monomorphic and the other is dimorphic. 1. Leaves dimorphic; sterile blades pinnatifid ......................................................... 1. W. areolata 1. Leaves all of one type, pinnate .......................................................................... 2. W. virginica 1. Woodwardia areolata (L.) Moore, Index Fil. 45. 1857. Fig. 2. Leaves dimorphic, deciduous; sterile leaves deeply pinnatifid, to 60 cm long, often nearly as broad, bright green, nearly glabrous when mature, the segments entire; petiole pale, becoming red-brown at base; fertile leaves pinnate, up to 30 cm long, the pinnae linear, up to 5 mm wide; sori linear-oblong, sunken into the blades. Bogs, seeps, wet woods, wet sandstone ledges. IL, IN, KY, MO, OH (OBL). Netted chain-fern. This species is more similar in appearance to the sensitive fern (Onoclea sensibilis) than to the other species of Woodwardia. The sterile leaves are most readily distinguished from the sterile leaves of Onoclea sensibilis by its segments being entire rather than finely toothed. 2. Woodwardia virginica (L.) Sm. Mem. Acad. Roy. Sci. (Turin) 5:412. 1793. Fig. 3. Leaves monomorphic, deciduous, up to 1 m long, pinnate, the blade with some glands; petioles pale, dark purple near the base; pinnae linear to narrowly lanceolate, up to 3.5 cm wide; sori elongated, linear, usually appearing confluent. Bogs, swamps, marshes. IL, IN, OH (OBL). Virginia chain-fern. This species is somewhat similar to young fronds of cinnamon fern (Osmunda cinnamomea), but the base of the petiole in the Virginia chain-fern is dark purple, while in cinnamon fern it is covered by a cinnamon-colored wool. Virginia chainfern is also...