POTAMOGETONACEAE 67 
10-celled, slightly sulcate between the cells at the apex, at maturity 
yellowish-red. ; 
Very common along the seashore and along tidal streams, Pasay, etc., fl. 
June—Sept., and probably in other months; throughout the Philippines near 
the sea. Mascarene Islands to southern Asia, Malaya, Australia, and 
Polynesia. 
Some horticultural forms are cultivated in Manila, but their botanical 
status is uncertain as flowers and fruits are unknown. A common form 
with shining, uniformly green, not at all glaucous leaves, is probably only 
a variety of Pandanus tectorius Sol.; another form quite similar to this but 
with some of the leaves variegated with white, or the upper ones nearly . 
or quite white is Pandanus veitchii Hort., which probably originated in 
Polynesia, and which may also well be only a variety of P. tectorius Sol. 
10. POTAMOGETONACEAE (PONDWEED FAMILY) 
Herbs growing in fresh or salt water, usually submerged, from slender 
rootstocks. Leaves usually distichous, opposite or alternate, submerged or 
floating, entire, linear to ovate, base sheathing. Flowers very small, perfect, 
in fascicles or spikes. Perianth none, or of 4 small sements. Stamens 
2, sessile or subsessile.- Ovary of 1 to 4 or more carpels, each 1-ovuled. 
Fruit a small, 1-seeded, cylindric or ovoid achene. 
Genera 9, species about 115, in fresh or salt water in ail parts of the 
world, 2 or 3 genera and 6 or 7 species in the Philippines. 
Spikes cylindric, many-flowered; stamens 4; perianth of 4 small segments; 
planpare? itrosh:iwater:* a2 222.252 acc kicen ietlesl el Eis 1. Potamogeton 
Flowers 2 to 6 within the leaf-sheath; stamens 2; perianth none; plants 
Of salt water with linear leaves:...2.:..i:00.100224-.1..408...2500... 2. Ruppia 
1. POTAMOGETON Linnaeus 
Perennial or annual, submerged or floating aquatic herbs, the stems weak, 
flaccid, branched, leafy. Leaves opposite or alternate, all submerged and 
sessile or the upper ones floating, often petioled, linear to oblong or elliptic. 
Spikes cylindric, terminal, mostly densely many-flowered, the scape from a 
membranaceous spathe. Flowers perfect. Perianth-segments 4, concave, 
green (dilated-winged connectives of the anthers of some authors). Anthers 
4, sessile on the segments. Carpels 4, sessile 1-celled, l-ovuled. Fruit 
small coriaceous or spongy, drupe-like. (From the Greek “river” and 
“neighbor” in reference to the habitat of most species.) 
Species about 87, with many varieties, in all parts of the world, about 4 
in the Philippines. 
1. P. malainus Miq. 
Stems elongated, slender, up to at least 2 m in length. Submerged leaves 
thin, lanceolate or oblong-lanceolate, mostly long-petioled, both ends acute, 
apex mucronate, 6 to 15 cm long, 1 to 1.5 cm wide, the midrib thick, the 
nerves slender, the margins of the younger leaves crenulate-undulate. 
Peduncles about as long as the leaves. Spikes slender, cylindric, up to 3.5 
em long, interrupted, about 5 mm in diameter. 
Abundant in the Mariquina River near Pasig, fi. Jan._Apr.; widely 
distributed in the Philippines. India to China, Formosa, Java, Sumatra, 
and Borneo, also reported from the West Indies. 
