34;•«fer
21. ARACEAE
upward by the enlarging spadix; spadix ca 3 cm long at anthesis; staminodia widely dispersed in clusters of 4 (rarely 5), to ca 3 cm long; staminate flowers ca 3.5 mm long, the perianth 20-30-lobed, glandular; pistillate flowers connate with each other, the tepals much reduced, the long, immersed stigmas sessile, longer than broad;
fruiting spadices 8.5-9.5 cm long, ca 1.5 cm diam, blunt, becoming orange, fleshy and tasty at maturity, the pedun- cles with 3 prominent spathe scars; stipes 5-7 mm long;
stigmas round, ca 0.5 mm diam. Fruits diamond-shaped, 11-17 mm long, 9-12 mm wide, conical; seeds numerous,
± ovoid, ca 1.5 mm long, embedded in a sweet, sticky, gelatinous matrix at maturity. Croat 12560.
Occasional, in the old forest. Reportedly flowers in June. Mature fruits have been recorded in November and December.
Obscurely resembling Stenospermation (21. Araceae), but distinguished by having more than one spathe.
Panama to Ecuador on the Pacific slope. In Panama, known from tropical moist forest in the Canal Zone and Darien.
See Figs. 78 and 79.
2I.ARACEAE 185 Plants epiphytic; peduncles not arising from the ground; spathe free; spadix
uniform:
Leaf segments lobed, usually more than 50 cm long Anthurium davigerum Poepp. & Endl.
Leaf segments entire, usually less than 30 cm long . . Anthurium bombacifolium Schott Blades with 3-5 lobes:
Blades round in outline; leaflets of approximately the same size and shape Anthurium bombacifolium Schott Blades not round in outline; leaflets not of uniform size and shape:
Plants juvenile; caudex short; leaves clustered at apex, commonly directly asso- ciated with entire leaves Anthurium davigerum Poepp. & Endl.
Plants adult; long vines; leaves well spaced, not directly associated with entire leaves:
Leaf veins all parallel, none impressed on upper surface, collecting veins lack- ing; milky sap lacking; spathe persistent; spadix lacking a sterile staminate part Philodendron tripartitum (Jacq.) Schott Leaf veins interconnected between major laterals, not parallel, the major veins
impressed above, the collecting veins 2 or 3; milky sap common; spathe deciduous; spadix bearing a sterile staminate part above the pistillate part Syngonium
• Leaf blades simple and entire, though often lobed at base:
• Leaf blades conspicuously cordate, sagittate, or hastate, lobed at base, the sinus at least one- fourth as long as blade:
Plants epiphytic:
Spathe linear-lanceolate, free; spadix uniform; reticulate venation prominent Anthurium broivnti Mast.
Spathe enclosing spadix; spadix divided into staminate and pistillate parts; reticulate venation lacking or not prominent (except P. hederaceum, which is also puberulent on petioles) Philodendron (in part) Plants terrestrial or aquatic, rooted in soil:
Plants acaulescent or with subterranean stem, sometimes pubescent:
Petioles puberulent, armed with short prickles in basal half Homalomena wendlandii Schott Petioles glabrous or pubescent, but not armed with short prickles Xanthosoma Plants with definite stem or caudex (the leaves sometimes closely clustered and appear-
ing acaulescent):
Plants commonly growing in standing water, the stem erect, at least 1 m tall, armed with short prickles at least in basal part; spathe deciduous in fruit Montrichardia arborescens (L.) Schott Plants never in standing water, the stem usually creeping over the ground, short, un-
armed; spathe persistent in fruit:
Petioles conspicuously flattened on upper surface; veins all parallel or at least without conspicuous reticulate veins; spathe enveloping spadix; spadix of staminate and pistillate parts Philodendron grandipes Krause Petioles terete; veins not all parallel, the reticulate veins prominent, forming a col-
lecting vein near margin; spathe free, narrow; spadix uniform with bisexual flowers:
Blades thick; sinus narrow or closed, the lobes often overlapping (at least when flattened out); fruits ± orange; plants growing usually at the margin of the lake on exposed areas (rarely in the forest except as an epiphyte) Anthurium brownii Mast.
Blades thin; sinus always broad, the lobes never overlapping; fruits violet- purple at apex, white at base; plants growing in forest Anthurium ochranthum C. Koch
• Blades never conspicuously lobed at base, or if cordate, with basal sinus much less than one-fourth the length of blade:
• Plants terrestrial (including those in standing water):
Plants acaulescent or nearly so, the caudex nearly subterranean; flowers bisexual (spa- dix thus uniform); spathe remaining open and persistent Spathiphyllum Plants caulescent with a thick stout stem, usually short, creeping along the ground then
erect; flowers bisexual or unisexual; spathe rather tightly enveloping spadix and persistent or caducous:
Major lateral veins close together, at ca 90° angle from midrib; petioles hard, nodose and geniculate at apex; spathe free, soon deciduous; spadix uniform (i.e., flow- ers bisexual) Rhodospatha moritziana (Schott) Croat Major lateral veins not close together, directed decidedly upward; petioles succulent,
not nodose or geniculate; spathe persistent, attached to lower part of spadix;
spadix with staminate and pistillate parts; sap with odor of oxalic acid Dieffenbachia
Plants epiphjTiic, never terrestrial at maturity except by accident:
Plants with fertile parts:
Spadix divided into staminate and pistillate parts; spathe persistent and enveloping spadix after opening; plants long epiphytic vines Philodendron (in part) Spadix uniform; spathe either deciduous or narrow and free after opening:
Spathe narrow, free at anthesis, usually persistent; leaf blades with or without col- lecting veins near margin; stigmas round or square; plants with or without elongate caudices Anthurium (in part) Spathe broad or convolute, usually surrounding spadix at anthesis (at least at
base), soon deciduous; leaf blades lacking colleaing veins; stigmas oblong or linear; plants with elongate caudices:
Blades small, less than 7 cm wide, the veins ± parallel to midrib; peduncles re- curved at apex before anthesis Stenospermation angustifolium Hemsl.
Blades very much larger, the veins not parallel to midrib; peduncles always ± erect:
Leaves entire, never perforate or pinnately lobed; primary lateral veins often 1 cm or less apart; caudex and petioles not finely tuberculate; stigmas round or ellipsoid Rhodospatha wendlandii Schott Leaves often perforate; primary lateral veins 1.5 cm or more apart; caudex
and petioles usually finely tuberculate; stigmas linear Monstera Plants sterile:
Blades with ± prominent reticulate veins between major lateral veins:
Blades perforated or pinnately lobed; plants long slender vines with many short roots at most nodes Monstera Blades entire, not perforated; plants usually with short caudices
Anthurium (in part) Blades with all lateral veins parallel or subparallel:
Lateral veins ± parallel to midrib Stenospermation angustifolium Hemsl.
Lateral veins never almost parallel to midrib:
Leaves pinnately lobed Monstera dilacerata C. Koch Leaves entire:
Petioles continuously canaliculate to base of blade Rhodospatha wendlandii Schott Petioles winged-vaginate but the sheath always ending short of blade (free
part of sheath may extend beyond base of blade in P. guttiferum) Philodendron (in part) similar to the scent compounds they seek in orchids
(Dodson et al, 1969; Hills et al., 1972). A male bee of Eulaema cingulata has also been reported to visit inflores- cences oiXanthosoma nigrum without taking either pollen or nectar (Dodson, 1966). The implication is that bees may be attempting to collect scent compounds from this species as they probably do from Spathiphyllum and Anthurium. Probably a similar system will be found for other genera with bisexual flowers, such as Monstera, Rhodospatha, and Stenospermation.
Rhodospatha moritziana has a whitish, syrupy sub- stance covering the spadix just after anthesis that may attract such insects as euglossine bees. Faegri and van der Pijl (1966) reported that these nectarlike substances are secreted by the stigmatic papillae but that the cell contents soon disintegrate. See Dracontium dressleri for a discussion of probable fly pollination (Croat, 1975c).
Fruits are endozoochorous, probably predominately ornithochorous, except perhaps those of Pistia and Spa- thiphyllum. This is especially true of Anthurium, which has colorful fruits that suddenly emerge from the tepals and may later be suspended slightly from two to four threadlike structures. All of the fruits of the spike may emerge at nearly the same time, as in A. bakeri and A.
friedrichsthalii, or they may be considerably staggered, as in A. tetragonum. Once exposed, they are quickly re-
moved. The seeds (usually two to four) are easily forced from the lower end of the berry and are embedded in a clear, jellylike, sticky mesocarp. After eating the sweet mesocarp (no doubt many seeds as well), the bird prob- ably has some seeds stuck to its bill. Whetting its beak on a distant tree, the bird deposits the seeds at an appropriate germination site, where they stick. Bats are also known to take fruits oi Anthurium (Yazquez-Yanes et al., 1975).
Fruits of Dracontium are probably dispersed in a man- ner similar to Anthurium. All genera with unisexual flowers, except Montrichardia, have the spathe completely covering at least the lower part of the spadix until the fruits mature. In the case of Dieffenhachia and Philoden- dron the pistillate part of the spadix is fused to the spathe, and the fruits are free. At maturity the inflorescence curls, rupturing the spathe and exposing the fruits. Seeds oi Dieffenhachia seem well suited for bird dispersal, but are probably taken by larger animals as well. In Philoden- dron the fruits are closely aggregated and are probably eaten by monkeys as well as birds. Leaf-cutter ants have been seen carrying the tiny seeds also, and no doubt some are dropped along the way. It is important to point out that, except in the case of Philodendron radiatum, seeds germinate on the ground. Later stages of the plant be- come hemiepiphytic or even truly epiphytic by climbing trees and losing their ground connection.
Caladium and Xanthosoma have closely congested fruits that are no doubt dispersed in a manner similar to Philodendron, though the spathe seems to fall more by decomposition than by arching of the inflorescence. In Syngonium the fruit is syncarpous, and the spathe falls free at maturity of the fruit. Fruits, while not colorful, are fleshy and sweet. The few, relatively large seeds may be swallowed when the tasty mesocarp is eaten. Fruits are probably taken mostly by monkeys but possibly by other animals as well. In Montrichardia, the only species having unisexual flowers and lacking a persistent enveloping spathe, the fruits are held in an irregular aggregate much larger than the fruits of any other genus. They are usually water dispersed, but are also reported to be eaten by the Hoatzin bird {Opisthocoma cristatus) in South America (Ridley, 1930).
All members of the tribe Monsteroideae, including Stenospermation, Monstera, Rhodospatha, and Spathi- phyllum, have fruits that are apparently unprotected by any structural modification such as a protective spathe.
Nicolson (1960) reported that all these genera contain trichosclereids; since in masses these cells may give hard- ness and mechanical protection (Eames & MacDaniels, 1947), it is possible that they play a part in preventing predation on immature inflorescences.
Monstera and Stenospermation have bisexual flowers with uniform inflorescences like Anthurium, but the pistils become united and form a syncarpous fruit. At maturity the periphery of the fruit exfoliates in sheets or
21. ARACEAE/ANTHURIUM 187 smaller segments, exposing the soft fleshy locules con- taining many small seeds. Fruits are probably taken by arboreal frugivores, including birds.
Fruits of Spathiphyllum are fully exposed and closely congested like the kernels of a cob of cqm, becoming rather loose and easily removed at maturity. They are probably taken by birds and other animals; I have seen large segments of an inflorescence removed as though from a single bite. Bunting (1965) reported that the fruits may be water dispersed. Vegetative reproduction of new plantlets that later split off is a clear possibility for the aquatic Pistia.
About 120 genera and 1,800 species; widely distributed but most numerous in the tropics and subtropics.
ANTHURIUM Schott
The genus Anthurium appears to be considerably more plastic in its variation in morphological characters than are most genera in the family, with the result that a large number of species have been described more than one time.
Anthurium may be distinguished by having a free spathe that is usually persistent. The spadix is cylindrical and uniform with bisexual flowers having four tepals;
the tepals are opposite the four stamens and more or less three-sided at the apex. Fruits have two locules with one or two ovules per locule.
KEY TO THE SPECIES OF ANTHURIUM Leaves compound:
Leaflets sessile, undulate or lobed; largest leaflets more than 50 cm long (on adult plants); spadix more than 40 cm long A. clavigemm Poepp. & Endl.
Leaflets petiolulate and entire; largest leaflets less than 30 cm long; spadix less than 15 cm long A. hombacifolium Schott Leaves simple:
Leaves ovate to triangular and cordate, with large basal lobes and a prominent sinus:
Blades coarse and leathery, drying very stiff, the margins wavy or folded, the sinus narrow or closed by overlapping basal lobes (at least on flattening); fruits ± orange; plants usually epiphytic except at lake margin A. hrownii Mast.
Blades thin, the margins never strongly wavy or contorted, the sinus usually open (sometimes closed), broad; fruits violet-purple at apex, white at base; plants always terrestrial on BCI A. ochranthum C. Koch Leaves without basal lobes or sometimes moderately cordate at base but without large basal
lobes and a deep sinus:
Blades without a collecting vein, the primary lateral veins extending apically near the margin and closely approaching or merging with it; large epiphyte with obovate to oblanceolate leaves and large, ± pendent inflorescences A. tetragonum Schott*
Blades with a collecting vein (the primary lateral veins joining before reaching the margin):
Plants scandent or with elongate, often branched, creeping caudices:
Blades acute at base, often punctate on lower surface; fruits white at maturity A. scandens (Aubl.) Engler Blades rounded at base, epunctate; fruits orange or red at maturity A. flexile Schott Plants not scandent, acaulescent or with short unbranched caudices:
• Plants lacking punctations:
Blades broadest at or about middle; cataphylls weathering, becoming fibrous, persist- ing on all but the oldest part of stem; spadix lavender at anthesis; fruits white ...
A. scandens (Aubl.) Engler Blades broadest usually well above middle; cataphylls not weathering into fibers, ulti-
mately deciduous; spadix not lavender at anthesis; fruits red A. gracile (Rudge) Lindl.
i88 MONOCOTYLEDONEAE
• Plants conspicuously punctate, at least on underside of leaf:
Blades usually more than 10 times longer than wide, of ca equal width throughout;
plants often pendent or at least the leaves not held stiffly erect; fruits truncate at apex, broader than long, pale yellow-orange A. friedrichsthalii Schott Blades usually less than 10 times longer than wide, considerably broader in distal half;
plants not pendent, the leaves held stiffly erect; fruits not as above:
Blades more than 11 cm wide; peduncles usually more than 30 cm long; blades ± thick, broadest at middle, gradually tapered to both ends .. A. acutangulum Engler Blades usually less than 11 cm wide; peduncles usually less than 30 cm long;
Blades thin, conspicuously acuminate at apex; collecting vein much more promi- nent than the lateral veins; spadix less than 11 cm long in flower (to 15 cm in fruit); fruits bright red A. hakeri Hook.f.
Blades thick, obtuse to acute at apex (often with short apiculum); collecting vein scarcely if at all more prominent than the lateral veins; spadix usually more than 11 cm long in flower; fruits yellowish or orange A. littorale Engler
*Discovered too late for treatment: A. concolor Krause, Notizbl. 107:617. 1932. Croat 8154 from Pearson Peninsula. Like A. tetragonum, but spadix violet-purple and petioles three-ribbed on lower side.
Anthurium acutangulum Engler, Bot. Jahrb. Syst.
25:371. 1898 A. porschianum Krause
Epiphyte; caudex short and thick, usually surrounded by a dense mass of roots; internodes short; cataphylls thin, short, weathering into brown fibers. Petioles stout, 9-18 cm long, with a deep narrow channel on upper surface, geniculate at apex; blades elliptic or oblong-elliptic, rounded or obtuse at apex and cuspidate-acuminate, mostly obtuse at base, 20^0 cm long, 11-15 cm wide, often arching with the tip curved downward, punctate on underside, ± thick, the major lateral veins in 10-15 pairs, forming a prominent colleaing vein near the mar- gin. Inflorescences spreading-pendent; peduncles 30-45 cm long; spathe green (pinkish elsewhere), lanceolate- acuminate, 9-11 cm long, less than 2 cm wide, withering in age; spadix sessile or short-stipitate, Unear, weakly tapered to apex, 15-30 cm long, 7-10 mm broad (4-5 mm when dried); tepals truncate at apex, sharply triangular, 2-3 mm wide. Mature fruits apricot-orange, ca 5 mm long, 5 mm wide (slightly wider in direction of axis), drying with small depression at apex. Croat 4347b, 6740.
Apparently rare, occurring in the forest and seen only on small trees within 2-3 m of the ground. Individuals produce successive inflorescences and may be found in flower all year, especially during the rainy season. The fruits probably develop promptly.
Perhaps most easily confused with^. littorale, which has narrower blades, often broadest below the middle, with reticulate venation usually as prominent on dry specimens as the lateral veins. Elsewhere in Panama the species is most easily confused with A. ramonense Engler ex Krause, a species with thick, oblanceolate-elliptic leaves, thicker petioles, and stouter spadices.
Honduras to Panama; sea level to 900 m. In Panama, known from tropical moist forest in the Canal Zone and Bocas del Toro, from premontane wet forest in Bocas del Toro, and from tropical wet forest in Colon and Panama.
See Fig. 80.
Anthurium bakeri Hook.f, Bot. Mag. 32, pi. 6261. 1876 Epiphyte; caudex short and thick, usually less than 10 cm long and 1.5 cm wide; internodes short, moderately
slender-rooted; cataphylls ± thick, 3-5 cm long, soon reduced to coarse, brown, persistent fibers. Petioles 3-17 cm long, to 5 mm thick, broadly canaliculate and straight to moderately geniculate near apex, broadened and shortly vaginate at base; blades elliptic-lanceolate, broadest at or about middle, rather abruptly acuminate at apex, acute at base and weakly decurrent onto margins of petiole, 19-44 cm long, 2.8-9 cm wide, bicolorous, only moder- ately thick when fresh, thin on drying, held erect largely by V-shaped construction of blade and by midrib, the midrib thick, prominently raised on underside, the lower surface densely punctate; collecting vein 3-8 mm from margin, prominent on both surfaces, especially the lower, the lateral veins obscure (moderately prominent on dried specimens). Inflorescences held ± erect; peduncles slen- der to moderately stout, 8-29 cm long, shorter than leaves; spathe green, reflexed, 2-5.5 cm long, 7-20 mm wide, acute and apiculate at apex, the margin often turned in, decurrent onto peduncle at base; spadix sessile to shortly stipitate, bluntly rounded at apex, 2-11 cm long and 5-7 mm wide in flower, to 15 cm long and 2.5 cm wide in fruit. Fruits obovate, acute to rounded at apex, ca 6 mm long, bright red, emerging from tepals and pendent, suspended on 2 slender white fibers; seeds 2, oblong, white, ca 3 mm long, somewhat flattened, em- bedded in a sticky, clear matrix. Croat 6627, 10882.
Uncommon, in the forest, usually at low elevations on reasonably small branches. Probably rare other places as well, since the plant has seldom been collected despite its prominently colored inflorescences and frequent flow- ering. Plants produce a continuing series of inflorescences throughout the year, especially during the rainy season, and fruits mature in 3-6 weeks.
Though possibly confused with A. littorale, which has thick leaves lacking a prominent collecting vein, A. bakeri is recognized by its thin, punctate blades, which are broadest at or about the middle, by the short spadix, which is scarcely if at all tapered toward the apex, and by its bright red berries.
Guatemala to Panama (in Costa Rica on the Atlantic slope as well as from the Osa Peninsula on the Pacific slope). In Panama, known from tropical moist forest on BCI and at Summit Garden in the Canal Zone and from premontane wet forest in Colon (Santa Rita Ridge).
See Fig. 81.