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

480 BURMANNIACEAE
Tillandsia usneoides (L.) L., (like Usnea, old-man’s-beard, a lichen that hangs from trees)
SPANISH-MOSS, OLD-MAN’S-BEARD, LONG-MOSS, BLACK-MOSS, PASTLE, FLORIDA-MOSS. Hanging
strands to 3–4(–8) m long; roots nearly always absent; leaves � thread-like, 2–3(–6) cm long, ca.
1–2 mm wide, densely scaly; inflorescence of a single flower; petals greenish or yellow-green.
Epiphytic or on wires or other supports; e and s parts of East TX; also Gulf Prairies and Marshes
and South TX Plains; se U.S. from VA s to FL w to TX. Feb–Jun. In moist areas in East TX, this
species often hangs in large, extremely conspicuous festoons from trees. It occurs from the s U.S.
s to Argentina, an incredible distribution stretching across 5,000 miles (8,047 km) of latitude. It
is distributed by the wind and by birds using it as nest material. The dried plants have long
been used in upholstery, as packing material (Kennedy 1841; Mabberley 1987), and in crafts and
floral designs. This superficially lichen-like species is strikingly different morphologically
from other members of the genus. However, mature plants of T. usneoides retain many characteristics
commonly found in the seedling stage of other members of the genus, and T. usneoides
is thus clearly linked to these other species (Tomlinson 1995). m/303
BURMANNIACEAE Blume
BURMANNIA FAMILY
Very small, delicate, apparently annual or possibly perennial herbs; leaves minute, bract-like;
flowers perfect, in small, head-like, racemose, or cymose clusters (can be solitary); perianth
segments 6, united, usually with free lobes; stamens 3; ovary inferior; fruit a capsule; seeds numerous,
small.
AA small (125–130 species in 13 or 14 genera, including Thismiaceae—Maas-van de Kamer
1998; Caddick et al. 2002b; Lewis 2002) primarily pantropical and warm temperate family that
occurs n to Japan and the e U.S. and s to New Zealand and Tasmania. The species are typically
small forest herbs. Based on molecular studies, it is now generally agreed that the family is related
to Thismiaceae (e.g., Caddick et al. 2002b; Neyland 2002), with some authorities combining
the families (e.g., Caddick et al. 2002b) and others recognizing two related families (e.g.,
Neyland 2002). While traditionally often described as saprophytic, Burmanniaceae are
mycophytic (= living symbiotically with fungi), and their manner of obtaining nutrition is
more accurately described as mycotrophic or myco-heterotrophic (= obtaining nutrition via
fungi) (Leake 1994). The family includes many mycotrophic species without chlorophyll,
while green-leaved species are hemimycotrophic, constituting a transitional stage between autotrophy
and heterotrophy. Fungi are located in special layers of cells in the roots (Maas-van de
Kamer 1998). Relationships of this family have long been controversial. It was previously considered
to be closely related to the Orchidaceae, based on the following shared characteristics:
epigynous, bilaterally symmetrical flowers, numerous small seeds, and mycotrophy (Rasmussen
1985). Subsequently, molecular and cladistic research suggests that the families are not related
and the similarities are due to convergence (Rasmussen 1995; Chase et al. 2000; Soltis et al.
2000). A number of molecular studies have suggested that Burmanniaceae is in the
Dioscoreales and thus more closely related to such families as Dioscoreaceae and Nartheciaceae
than to Orchidaceae (which is in order Asparagales) (Chase et al. 1995b; Caddick et al. 2000,
2002b; Chase et al. 2000). In contrast, other recent molecular research including more genera
than previously sampled indicates that the family (minus the superficially similar but unrelated
genus Corsia now in the Corsiaceae) plus Thismiaceae is in a relatively isolated position
“not closely aligned with either the Dioscoreales or the Orchidaceae” (Neyland 2002). Additional
research will be needed to clarify the relationships of this family. It has been suggested
that the numerous tiny seeds are dispersed by water (Maas et al. 1986). (subclass Liliidae—
Cronquist; order Dioscoreales—APG II)