A robust climber on large trees, to 15 m tall. Juvenile: a shingle plant, the stem strongly flattened. Adult stem: brown, roughly tuberculate, subterete, 3 – 4 cm thick, internodes 3 – 6 cm long, the stem often covered with the fibrous remains of petiole sheath wings; axillary bud in a depression extended into a sulcus; adventitious anchor roots numerous, feeder roots rare or absent. Petiole: smooth or tuberculate, densely flecked with white spots, 30 – 55 cm long, vaginate to the geniculum, the sheath wings deciduous, sometimes persisting as fibrous remains at the base of the petiole, geniculum 3 – 4 cm long, often of a rough texture and dark brown. Lamina: bright green, often remaining so in dried specimens, of a soft texture, not glossy, trichosclereids absent; 60 – 120 cm long, 35 – 60 cm wide, ovate to oblong-ovate, cordate at the base, the tip acute, pinnatifid and perforate, the perforations elliptic, 3 – 6 cm long, in 1 – 3 series per side; primary lateral veins 12 – 18 in number, prominent below and above, milk white, secondary lateral veins reticulate. Peduncle: terete, 1.5 – 2.5 cm thick, 14 – 18 cm long, tuberculate. Spathe: white, obovate, 15 – 18 cm tall, blunt or shortly mucronate. Flowering spadix: deep green to greenish gold, 14 - 19 cm long, 3.5 - 5.5 cm thick, in dried specimens a golden color, the apical surface of the pistils underlain by a layer if sclereids which form a sharp-edged papery cap in dried specimens.
Monstera punctulata is easily recognized by a number of features, among them its brilliant green leaves of a soft texture. These leaves lack trichosclereids, and this is the only species in which I have observed damage to the leaves by leaf cutter ants, suggesting that the abundant trichosclereids in the leaves of other Monstera species may be a defense against such predation. Other features of note are the densely white-spotted petiole with a brown tuberculate geniculum, the prominent white lateral veins of the lamina, and the dark green fruits which dry a golden color.
Monstera punctulata is a rare species in most of its range and is known from a relatively few collections. It is not uncommon in the limestone areas of the central Petén; I collected only a single specimen there as it was not in flower. Later I discovered that this was the first collection of the species from Guatemala.