Halophila stipulacea is a euryhaline marine angiosperm, also known as a seagrass. Plants are dioecious with male and female flowers produced at each leaf node. Rhizomes are creeping, branched and fleshy, and roots appear solitary at each node of the rhizome, unbranched and thick with dense soft root hairs. Pairs of leaves are distributed on petioles along a rhizome, rooted in the sand. Petioles are 3 - 15 mm long while leaves are 3 - 8 mm wide and obovate, hairy and not narrowing at base; margin spinulose (Galil, 2006).

H. stipulacea displays high morphological and genetic variability to differing enviornmental and ecological factors (Procaccini et al., 1999). Stands at comparable depths from different localities were found to be genetically more similar (Procaccini et al., 1999).
Two unidentified photosynthetic pigments with the same retention time as two “siphonaxanthin-type\" pigments were isolated and relatively common in H. stipulacea. This could perhaps be a biochemical adaptation to different light regimes in seagrass species that can colonise deeper habitats (Casazza & Mazzella, 2002).

In its native range, Halophila stipulacea occupies soft marine sublittoral sediments, growing in sheltered localities as isolated patches, on muddy bottom and coral rubble (Galil, 2006). In its introduced range, H. stipulacea also occupies marine sublittoral sediments intertidal to 65 m, but mainly at a depth of 30 - 45 m, usually in or in the vicinity of harbours (Galil, 2006).

Halophila stipulacea is dioecious with male and female flowers produced at each leaf node (Galil, 2006). These flowers of are solitary, with the axillary covered by spathes (Galil, 2006). Strings of four reniform trinucleate pollen grains contained in a mucilaginous moniliform tube are dispersed (Galil, 2006). In India, female flowers and fruits are noticed from February to April while in the Mediterranean, the main flowering season occurs in July-August, with fruits ripening in September (Galil, 2006). Experimental studies demonstrated that full sunlight completely inhibited seedling growth at a depth of 30 cm which may explain the absence of H. stipulacea from the uppermost part of the subtidal zone (depths of 0–2 m) (Malm, 2006). It is suggested that, as only male flowers are usually found in the Mediterranean area (Procaccini et al., 1999), it may be difficult for female flowers to develop in the Mediterranean climate (Gambia et al., 2009). This implies that main propagation of the species is by fragmentation and vegetative stolonization (Gambia et al., 2009).

Halophila stipulacea is dispersed to new locations via current or vessel-borne plant fragments or fruits (Galil, 2006).

Halophila stipulacea is capable of out-competing native Mediterranean seagrasses while inducing changes in the composition of sublittoral communities (Galil, 2006). Tsiamis et al. (2010) state that while the high abundances of H. stipulacea observed may indicate invasive behaviour, no reports of native species displacement have yet been made. Williams (2007) states that no ecological consequences of the introduction and spreading of H. stipulacea have been reported, as H. stipulacea might be small enough to co-exist under the canopy of the larger native seagrasses.

Halophila stipulacea is included in the \"100 Worst Invasive Alien Species in the Mediterranean\" list due to its potential to cause serious negative impacts on biodiversity (Streftaris & Zenetos, 2006). Halophila stipulacea is also included in the '100 of the worst aliens species in Europe' list (see Delivering Alien Invasive Species Inventories for Europe (DAISIE))

Preventative measures: The erection of a salinity barrier in the Suez Canal was mentioned in Galil (2006) to reduce the number of alien species such as Halophila stipulacea from entering the Mediterranean Sea.