Glabrous, parasitic shrubs or vines; nodes usually swol- len, the internodes with scalelike cataphylls. Leaves opposite, sessile or petiolate; blades simple, entire, leath- ery; venation generally obscure (may be palmately veined at base); stipules lacking. Flowers bisexual or unisexual (dioecious or monoecious), actinomorphic, borne on a cupular receptacle (the calyculus) in axillary spikes of few to many flowers; perianth in 1 or 2 similar series, the outer series truncate or 4- or 6-parted, the inner series (lacking in ours) 6-parted; stamens equal in number to
perianth lobes and borne on them; anthers 2-celled, gen- erally introrse, dehiscing longitudinally, often with a connective extending above the thecae; ovary inferior, formed by the receptacle, 1-locular (obscurely so), pre- sumably 3- or 4-carpellate; placental area central, basal;
ovule 1; style 1, simple; stigma capitate or lacking in staminate flowers. Fruits berries; seeds few, with en- dosperm.
This family of parasitic shrubs with brittle stems is not confused with any other. Plants are particularly con- spicuous in the dry season if their host happens to be a deciduous tree. All species are photosynthetic and at- tached firmly by modified roots (haustoria), which connect directly to the vascular system of the host. No systematic study has been made with regard to host preference but, if any exists, it is not apparent. The Citrus species (67.
Rutaceae) of the Laboratory Clearing abound with a number of species of Loranthaceae, especially Oryctan- thus and Phthirusa pyrifolia, but this is perhaps due to the fact that these trees are roosts for a multitude of birds.
Sexual parts of the opposite sex for species with unisexual flowers may be absent altogether as in Phoradendron or merely reduced and sterile as in Struthanthus.
The minute greenish flowers are pollinated by small insects (Kuijt, 1969).
The sticky-seeded berries are typically bird dispersed (Ridley, 1930; Kuijt, 1969). Seeds are frequently seen germinating on tree branches where birds have roosted.
Van der Pijl (1968) reported that some Loranthaceae have seeds with a built-in water reserve, which allows them to germinate on dry branches in the absence of water.
About 30-40 genera with 1,000-1,400 species; mainly in the tropics.
KEY TO THE SPECIES OF LORANTHACEAE
Rachis of the spike with depressions in which the flowers and fruits are attached:
Spikes of several joints with bracteoles beneath each joint; stems with paired scales (cataphylls) on some of the internodes, at least on the lowermost internode of each branch; tepals 3:
Scales present at the base of each internode; stems terete; leaves more than 2.5 cm wide, acuminate Phoradendron piperoides (H.B.K.) Trel.
Scales present only on the lowermost internode of each branch; stems 4-angled when young;
leaves less than 2.5 cm wide, not acuminate Phoradendron quadrangule (H.B.K.) Krug & Urban Spikes lacking joints or bracteoles; stems lacking paired scales; tepals 6:
Leaves more or less cuneate; fruits attached perpendicularly to and entirely exposed from rachis; rachis glabrous, less than 2 mm wide Oryctanthus occidentalis (L.) Eichl.
Leaves rounded or cordate at base; fruits attached antrorsely to and partly sunken into cavities of rachis; rachis scaly, more than 2 mm wide:
Leaves petiolate, rounded at base; stems terete Oryctanthus alveolatus (H.B.K.) Kuijt Leaves usually sessile, cordate at base; stems usually sharply 2 (4)-angled
Oryctanthus cordifolius (Presl) Urban Rachis lacking depressions:
Plants herbaceous vines, usually much more than 1 m long; leaves orbicular, less than 5 cm long;
flowers more than 5 mm long; fruits ca 10 mm long Struthanthus orbicularis (H.B.K.) Blume Plants shrubs, to ca 1 m long; leaves ovate-elliptic, more than 5 cm long; flowers less than 2 mm
long; fruits ca 5 mm long Phthirusa pyrifolia (H.B.K.) Eichl.
ORYCTANTHUS Eichl.
Oryctanthus alveolatus (H.B.K.) Kuijt, Bot. Jahrb.
Syst. 95(4):504. 1976 Mato palo
Erect, parasitic shrub; stems terete, to 70 cm long; peri- derm rufous-scaly but glabrescent. Leaves glabrous; peti- oles short, to 5 mm long; blades ± ovate, rounded at apex and base, slightly decurrent on petiole, not at all clasping stem, 4-9 cm long, 3-5.5 (rarely 9) cm wide, coriaceous, drying brownish; venation palmate, the midvein not reaching apex, the principal vein usually branching.
Spikes axillary, usually 2 per axil, 2-3.5 cm long, sessile or on rufous peduncles to 5 mm long; rachis becoming more than 3 mm wide in fruit, reddish, scaly; flowers sunken into pockets in rachis, oblique to the rachis; mar- gins of bracteoles united with rachis, appearing indistinct from rachis; flowers minute, bisexual, greenish; tepals 6;
stamens 6, the filaments fused to tepals; anthers strongly dimorphic, the 2 inner pollen sacs much smaller than the outer ones; style 1. Fruits ovoid-oblong, ca 5 mm long, greenish, sometimes with yellowish base, the apex ex- ceeded by the margin of the persistent, oily calyculus;
seed 1, obdeltoid, ca 2 mm long, drying black. Croat 6566.
Frequent along the shore and at the edges of clearings.
Flowers and fruits throughout the year.
This species was confused with O. spicatus (Jacq.) Eichl. in the Flora of Panama by Rizzini (1960) and by Standley in the Flora ofBarro Colorado Island (1933). O.
spicatus ranges from Guatemala to Venezuela, Brazil, and Peru. It has not been reported from Panama, but is to be expected, since it occurs in Colombia (Choco).
Costa Rica to Colombia, Venezuela, the Guianas, Brazil, and Bolivia; Trinidad. In Panama, known from tropical moist forest in the Canal Zone, Herrera, Panama, and Darien, from tropical dry forest in Code, from pre- montane moist forest in the Canal Zone and Panama, and from premontane wet forest in Chiriqui.
Oryctanthus cordifolius (Presl) Urban, Bot. Jahrb.
Syst. 24:30. 1898
Erect, parasitic shrub; stems prominently 2 (4)-angled, especially when young. Leaves sessile, thick, ovate, ob- tusely acute to rounded at apex, rounded to cordate at base, 7-12 cm long, 4-8 cm wide, the lateral veins from near the base 7-9, obscure, visible when dried. Spikes axillary, solitary, 1-8 cm long; peduncles 5-15 mm long;
bracteoles with margins free; flowers and buds red, sunken obliquely into rachis in 4 distinct rows; tepals 6, ca 2 mm long. Fruits ellipsoid to obovoid, 5 mm long, 2.5 mm wide, perpendicular to axis, 1-seeded, purplish- black when mature (Kuijt, 1976). Shattuck 425.
The Shattuck collection has not been located but it is assumed to have been properly identified; the species has been collected elsewhere in the Canal Zone. Appar- ently flowers and fruits all year.
The species is similar to O. occidentalis except for its usually two-sided stem and cordate leaf blades.
Mexico to Caribbean and Pacific Colombia, Guyana
42.
LORANTHACEAE/PHORADENDRON367
(based on a single collection). In Panama, ecologically
~~ variable; known from tropical moist forest in the Canal Zone, Bocas del Toro, Colon and Panama, from tropical dry forest in Code (Penonome), from premontane moist forest in Panama (Punta Paitilla), and from premontane wet forest in Code (El Valle).
Oryctanthus occidentalis (L.) Eichl. in Mart., Fl.
Brasil. 5(2):89. 1868
Erect, parasitic shrub; stems terete, usually less than 60 cm long; periderm rufous, scaly. Leaves glabrous; petioles lacking or to 5 mm long; blades ovate (may be lanceolate when young), acute to rounded at apex, ± obtuse at base and decurrent on petiole but not clasping stem, 7-11 cm long, 2-7 cm wide, coriaceous, shiny, green (bronze when young), drying chestnut and green, the veins purple.
Spikes axillary, usually 2 or 3 per axil, conelike, to 3 cm long; peduncles rufous, 5-10 mm long; rachis to 2 mm wide (rarely to 3 mm), green, glabrous; flowers bisexual, sunken in rachis, perpendicular to the rachis and arranged in 4 rows; margins of the bracteoles distinct from the rachis; tepals 6, dimorphic, green, acute at apex, ca 1.2 mm long; stamens 6, each fused to lower part of tepal;
filaments red; anthers dimorphic, both types at or above middle of tepal, each with 4 locules or with 2 locules, or both these types alternating, then the 4-celled anthers lower than the 2-celled anthers, the connective extending above thecae; style simple; stigma capitate, held at about the level of the anthers; nectariferous disk surrounding style at base (Kuijt, 1976). Fruits cylindrical, to 4 mm long and 2 mm wide, yellow- and green-striped, drying dark; seed 1, ellipsoid, ca 1 mm long, brown. Croat 6443.
Common, often in exposed, sunny areas, especially along the shore. Even individual plants may flower throughout the year.
The fruits are taken by a variety of birds, including pigeons, manakins, flycatchers, tanagers, and finches (Leek, 1972).
Costa Rica to Ecuador, Venezuela, the Guianas, Brazil, and Peru; Jamaica. In Panama, known from tropical moist forest in the Canal Zone, Bocas del Toro, Colon, Chiriqui, Panama, and Darien and from premontane wet forest in Bocas del Toro, Code, and Panama.
See Fig. 211.
PHORADENDRON Nutt.
Phoradendron piperoides (H.B.K.) Trel., Monogr.
Phoradendron 145. 1916
Monoecious, parasitic shrub; stems terete, branched, green when fresh (drying rugose with a yellowish cast), a pair of cataphylls on almost every internode, the lower internodes usually with 2-5 pairs of cataphylls. Petioles less than 5 mm long; blades obliquely ovate, bluntly acu- minate, ± cuneate at base, 6-13 cm long, 2.5-5.5 cm wide, coriaceous, green when fresh, drying rugose and brownish to almost black if young, glabrous, often mar- ginally crisped, the veins lacking or obscurely pinnate on underside. Inflorescences of axillary, jointed spikes
^
;iii *•^••••••- ^.
'tl ,
. * . %'^ftlF • :-:;ifc:;'!:!: - ,* J w
. *» * •-. '. J * ,<r: * %
"'7 ,:'^ M f* ••-" ' • \^ ""'• *
if 1 1*
1
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s ""ft**1
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V:r,,, ' t "
ft J.1,
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II
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Fig. 211. Oryctanthus occidentals
Fig. 212. Phoradendron piperoides
42.
LORANTHACEAE/STRUTHANTHUS369
2.5-4.5 cm long, the spikes 4-6(8) per node, the joints 4-6 per spike, each subtended by two small, perfoliate bracts to 2 mm long; peduncles obscure or lacking; flow- ers unisexual, yellow, generally 12-20 per joint, 4-ranked, minute; tepals 3. Fruits attached from depressions in the rachis, ellipsoid, ca 4 mm long when mature, pale yellow to orange-brown. Croat 8408.
Occasional, in open areas and along the shore. Flowers and fruits from January to August.
The proper name for this species cannot be P. piper- oides (H.B.K.) Trel. J. Kuijt (pers. comm.), who has studied the type of Loranthus piperoides H.B.K., reports that it is not the same species as that going by the name P. piperoides. Until someone can study the types of other old synonyms, however, the name will be used.
Mexico to Argentina; West Indies. In Panama, known from tropical moist forest in the Canal Zone, Bocas del Toro, Code, Panama, and Darien, from premontane wet forest in Bocas del Toro and Chiriqui, and from pre- montane rain forest in Chiriqui.
See Fig. 212.
Phoradendron quadrangule (H.B.K.) Krug & Urban, Bot. Jahrb. Syst. 24:35. 1897
P. seibertii Rizz.; P. venezuelense Trel.
Mahoho, Mongreo
Monoecious, parasitic shrub, ± glabrous, only the inflo- rescence obtaining a yellowish cast when dry; stems square at least when young, a pair of cataphylls on only the lower internode of each branch. Petioles ca 2 mm long; blades elliptic-oblong, somewhat asymmetrical, mostly rounded at apex, sometimes mucronulate, atten- uate to the base, 3-6 cm long, 0.7-2.5 cm wide, coria- ceous, drying green to brown, rugulose, glabrous, the veins 3 and parallel or lacking. Spikes axillary, jointed, 1 or 2 per node, 1.5-4 cm long, the joints 3 or 4 per spike, each subtended by 2 minute bracts to 15 mm long; pe- duncles 3-10 mm long; flowers yellowish-green, generally 10-24 per joint, minute; tepals 3. Fruits attached from depressions in the rachis, globose, ca 3 mm long, yellow.
Croat 7398.
Occasional, in the Laboratory Clearing. Flowers and fruits throughout the year.
Panama, Colombia, and Venezuela; West Indies. In Panama, known from tropical moist forest in the Canal Zone, Bocas del Toro, Colon, Veraguas, Panama, and Darien, from tropical dry forest in Herrera and Code, and from premontane moist forest in the Canal Zone, Los Santos, and Panama.
See Fig. 213.
PHTHIRUSA Mart.
Phthirusa pyrifolia (H.B.K.) Eichl. in Mart., Fl. Brasil.
5(2):36. 1868
Parasitic shrub, sometimes to about 1 m long; branches flattened, 2-edged (especially the younger ones), the scurfy margins extending onto midrib of blades. Leaves
glabrous; petioles 3-10 mm long; blades ovate-elliptic, obtuse to rounded at apex, rounded at base, 5-10 cm long, 3-5 cm wide, coriaceous, the veins often visible.
Spikes 1 or 2 per axil, to 15 cm long; flowers bisexual, 4-6-parted, maroon, 1-2 mm long, in sessile ternations, these widely spaced along the furfuraceous, lenticellate spikes; calyculus truncate; tepals valvate, oblong, acute;
stamens shorter than tepals; filaments thick, fused to lower half of tepal; anthers about as broad as long, held at the level of the style; ovary red; stigma sessile; nectary prominent, the nectar rather copious. Fruits oblong, ca 5 mm long, becoming yellow or orange at maturity, dry- ing gray to brown; exocarp thin but leathery; mesocarp sticky, white; seed 1. Croat 6812, 7919.
Common in trees of the Laboratory Clearing; frequent elsewhere. Flowers and fruits throughout the year.
The fruits are a favorite of small birds.
Belize to Peru, Bolivia, and Brazil. In Panama known from tropical moist forest in the Canal Zone, Bocas del Toro, Colon, and Veraguas, from premontane moist forest in Panama, and from premontane wet forest in Chiriqui, Panama, and Darien.
STRUTHANTHUS Mart.
Struthanthus orbicularis (H.B.K.) Blume in R. & S., Syst. Veg. 7(2):1731. 1830
Mam rama, God bush
Dioecious, somewhat woody, glabrous, parasitic vine;
stems terete with thick adventitious roots at the nodes.
Petioles ca 1 cm long, sometimes twining, if so their blades reduced; blades suborbicular, rounded at apex, obtuse at base, 3-5 cm long, 2.5-4 cm wide, coriaceous, the veins generally apparent. Flowers with strong, sweet aroma, greenish or greenish-yellow, fairly conspicuous, 5-7 mm long, in sets of 3 on slender spikelike inflores- cences to 15 cm long, the ternations ± sessile; tepals 6, slender, free, acute, spreading above middle; stamens of staminate flowers fused to lower half of tepals, exserted at anthesis (above recurving tepals); filaments thickened just below anther (providing some protection to nectary), 3 filaments somewhat longer than the others; anthers introrse, about as broad as long; stigma held midway between upper and lower sets of anthers; nectary small, the nectar not copious. Fruits ellipsoid, ca 1 cm long, faintly orange to rust-red or purple, with copious milky latex; seed solitary. Croat 12620, White 121.
Uncommon, on trees near the edge of the lake in the vicinity of Colorado Point and Gigante Bay. Flowers and fruits from January to September.
Mexico to Peru and western Brazil. In Panama, wide- spread and ecologically variable; known from tropical moist forest in the Canal Zone, Bocas del Toro, San Bias, Veraguas, Panama, and Darien, from premontane dry forest in Herrera and Code, from tropical dry forest in Panama (Taboga Island), from premontane moist forest in the Canal Zone, Los Santos, and Panama, from pre- montane wet forest in Chiriqui and Code, and from premontane rain forest in Darien (Cerro Pirre).