POTAMOGBTONACEAE 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 Pandcmua veitchii Hort., which probably originated in 

 Polynesia; and which may also well be only a variety of P. tectorius Sol. 



10. POTAMOGBTONACEAE (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 all 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; 



plants of fresh water ;. 1. Potamogeton 



Flowers 2 to 6 within the leaf -sheath; stamens 2; perianth none; plants 



of salt water with linear leaves..-. , 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, 1-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 

 cm long, interrupted, about 5 mm in diameter. 



Abundant in the Mariquina River near Pasig, fl. Jan.-Apr.; widely 

 distributed in the Philippines. India to China, Formosa, Java, Sumatra, 

 and Borneo, also reported from the West Indies. 



