keys to the vascular plants of east texas - Botanical Research ...

356 OPHIOGLOSSACEAE/BOTRYCHIUM
OPHIOGLOSSACEAE (R. Br.) C. Agardh
ADDER’S-TONGUE FAMILY
East TX species terrestrial; stems � subterranean, simple, unbranched, upright; leaves 1 or less
commonly 2(–3) per stem, often ephemeral, divided into a blade portion (= trophophore) and a
fertile sporangia-bearing portion (= sporophore); blade portion simple, divided, or compound;
fertile portion lacking blade-like tissue, typically consisting of a long stalk with a terminal,
branched or unbranched, sporangia-bearing area; sporangia large (in comparison with those of
most other ferns), spherical, thick-walled, borne in 2 rows on each branch or on the unbranched
sporangia-bearing area.
AA nearly cosmopolitan family of 5 genera and ca. 70–80 species (Wagner & Wagner 1993) of
eusporangiate ferns (= with large sporangia having hundreds to thousands of spores per sporangium).
The Ophioglossaceae are thought by some (e.g., Kato 1988) to be only distantly related
to other ferns. Wagner (1990) indicated that “Of modern plants normally classified as
‘ferns,’ the Ophioglossaceae are the most isolated.” They are apparently relicts of an ancient lineage
(Bell & Woodcock 1983), and a number of characteristics “… suggest closer affinities to
progymnosperms or cycadophytes than to typical modern ferns” (Wagner 1990). Likewise, molecular
evidence (e.g., Vangerow et al. 1999), suggests that Ophioglossaceae and Marattiaceae
(e.g., Angiopteris) are in a clade which is the sister group to all other ferns. Recent phylogenetic
work (Pryer et al. 2001) confirms the isolated position of Ophioglossaceae and Marattiaceae at
the base of the fern lineage and indicates that the closest relative of these families is the
Psilotaceae. The Ophioglossaceae is made up of two clearly defined subfamilies, Botrychioideae
and Ophioglossoideae, sometimes recognized as distinct families. The young leaves unfold
rather than having the form of an unrolling fiddlehead as in most ferns (conduplicate rather
than circinate) (Kato 1988; Wagner 1990; Nelson 2000). Members of this family obtain minerals
through fungi associated with their fleshy roots (which lack root hairs); in essence these ferns
trade carbon compounds for minerals (J. Peck, pers. comm.). The following treatment draws
heavily on Wagner and Wagner (1993).
FAMILY RECOGNITION IN THE FIELD: often small plants with only 1 or sometimes 2(–3) leaves;
leaves with a blade portion (simple to compound) and an erect, spike-like, fertile portion consisting
of an elongate stalk and a terminal, fertile, sporangia-bearing area.
REFERENCES: Clausen 1938; Correll 1956, 1966a; Thomas 1972, 1980; Kato 1988; Wagner 1990;
Wagner & Wagner 1993; Vangerow et al. 1999; Pryer et al. 2001.
1. Leaf blades ternately-pinnately compound, divided, or lobed, the margins usually denticulate to
serrate or lacerate; veins of leaf blades dichotomous (= equally 2-forked) and free (= with their
distal ends unconnected to other veins); sporangia in a pinnately branched, panicle-like
arrangement ___________________________________________________________________ Botrychium
1. Leaf blades simple, the margins entire; veins of leaf blades reticulate and anastomosing (= veins
connecting by cross-veins to form a network); sporangia in an unbranched, linear, spike-like
arrangement _________________________________________________________________ Ophioglossum
BOTRYCHIUM Sw. GRAPE FERN, MOONWORT
Blade portion of leaf compound, divided or lobed, ovate to triangular or broadly triangular in
outline, � ternate (= divided into three � equal parts); fertile portion of leaf consisting of an
elongate stalk terminated by a 1–2-pinnate, panicle-like, sporangia-bearing region.
AA nearly cosmopolitan genus of 50–60 species (Wagner & Wagner 1993) with greatest diversity
at high latitudes and high elevations. Most species are quite variable vegetatively, resulting
in considerable taxonomic confusion. Plants typically produce only one leaf each year
(Nauman et al. 2000). (Latin: botry, bunch (of grapes), in reference to the sporangial clusters)