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

ARACEAE
463
hemiepiphytes, and aquatics (Croat 1988 [1990], pers. comm.). A number are used as food crops
and many species are valued as ornamentals. Food crops include the edible starchy corms of
Colocasia (TARO), Xanthosoma (TANIER), and Alocasia macrorrhiza (L.) G. Don (UPRIGHT EL-
EPHANT-EARS). Ornamentals include Anthurium (PAINTER’S PALETTE), Caladium, Dieffenbachia
(DUMB-CANE), Monstera, Philodendron, Pothos, Spathiphyllum (PEACE-LILY or WHITE-SAILS), and
Zantedeschia (CALLA-LILY). According to Croat (1994), the Araceae is the most important family
for indoor foliage plants in North America. � Many Araceae have tissues containing raphides
(= bundles of microscopic, needle-like calcium oxalate crystals) which are sometimes barbed
and grooved and which reportedly cause injury to the mouth, throat, or hands by puncturing
cell membranes (Prychid & Rudall 2000; Burrows & Tyrl 2001). However, properly cooked
plants which still contain the crystals generally do not cause irritation—therefore, the reaction
is apparently caused at least in part by other compounds (Thompson 2000b). The plants are
also often cyanogenic or contain alkaloids, free oxalic acid, proteolytic enzymes, or other toxins;
some are potentially fatally poisonous (McIntire et al. 1992; Woodland 1997). Philodendron, one
of the most popular house plants in the U.S., has raphides and questionable unidentified proteins
and can cause painful burning to the mouth and throat, as well as contact dermatitis.
Some reports suggest the leaves, if ingested, are highly toxic to cats; the plants should not be left
within reach of children or pets (Lampe & McCann 1985; Spoerke & Smolinske 1990; Burrows
& Tyrl 2001). Dieffenbachia (DUMB-CANE), another common house plant, contains raphides and
the alkaloid protoanemonine. Ingestion causes burning, hypersalivation, and swelling of the
tongue, pharynx, and larynx, and can result in death through suffocation. The common name
is derived from its ability to cause speech to become slurred and unintelligible, or even to paralyze
the vocal cords and render speech impossible. It is believed that the stems and leaves of
DUMB-CANE were used in the Caribbean to punish and silence rebellious slaves (Morton 1982;
Foster & Caras 1994; Bruneton 1999). Members of Araceae are pollinated by insects, some by
flies attracted by the odor of carrion (e.g., in Amorphophallus with huge inflorescences). In
some genera (e.g., Arisaema, Arum) there is a “kettle trap” pollination mechanism (Mayo et al.
1998) by which pollinators are trapped for some period of time in the kettle-like spathe (thus
increasing the probability of pollen transfer). Some species of Araceae can produce heat in the
inflorescences (thermogenesis), which volatilizes odors to attract pollinators (Proctor et al. 1996;
Bown 2000). The genus Acorus, traditionally placed in the Araceae, is here recognized in the
Acoraceae. The Lemnaceae (DUCKWEED family) is considered by many authorities to have
evolved from within the Araceae by neotenous reduction (= retention of juvenile characteristics in
a mature organism), and it has been suggested that Lemnaceae be reduced to a subgroup within a
more inclusive, monophyletic Araceae. As currently treated, the Araceae may thus be
paraphyletic and from the cladistic viewpoint inappropriate for formal recognition (French et al.
1995; Mayo et al. 1995, 1997, 1998; Stockey et al. 1997). For more information see discussion under
the genus Pistia. Molecular analyses (e.g., Fuse & Tamura 2000; Chase et al. 2000; Soltis et al.
2000) indicate that Araceae are phylogenetically near the base of the monocotyledons—
Acoraceae are the sister group to all other monocots, with Araceae (and Alismataceae and other
Alismatales) in the next most basal clade. Family name from Arum, a genus of 26 species of Europe
and the Mediterranean area. (Greek: aron, the classical name of these plants, possibly derived
from Arabic: ar, fire (Bown 2000), in reference to the burning caused by ingestion of some species)
(subclass Arecidae—Cronquist; order Alismatales—APG II)
FAMILY RECOGNITION IN THE FIELD: herbaceous perennials (also 1 floating aquatic) with numerous
very small flowers on an often finger-like spadix subtended by a sheath-like spathe; leaves
usually basal, with expanded blades, often with net venation.
REFERENCES: Birdsey 1951; Wilson 1960; Plowman 1969; Jacobsen 1985; Nicolson 1987b; Ray
1987, 1988; Bown 1988, 2000; Croat 1988 [1990], 1994; Grayum 1990, 1992; Bogner & Nicolson
1991; French et al. 1995; Mayo et. al. 1995, 1997, 1998; Thompson 1995, 2000b; Bogner 1997[1998];
Croat 1998.