228 THB TASMANIAK FLOBA. 



till the flower reaches the surface, where the pollen is discharged. Subsequent 

 to impregnation the carpels each develop a stalk, often ^-1 inch long. 



Very common in brackish water ; also throughout Australia. PI. summer. 



4. POSIDONIA. 



Flowers hermaphrodite or mostly so. Perianth none. Anthers 3, on a short 

 common filament. Ovary of a single 1-seeded carpel. Fruit with a succulent 

 pericarp. 



The genus contains but 3 species, 2 of which are European. 



P. AUSTEALis, Hook. Leaves flat, sheathing, clustered round the short stem, 

 1-3 feet long and about | inch wide. Flowering stems 1-2 feet long, bearing 3 or 

 4 spikes at a distance from one another, each about 2 inches long. Flowers 6-12 

 in each spike, each flower subtended by a bract and 2 bracteoles. Stigma 

 2-4-lobed. Fruit about | inch long. 



Near George Town, below low-water mark also in South Australia, West 

 Australia, and Victoria. Fl. Dec. 



5. ZOSTERA, 



Flowers unisexual, but in the same inflorescence, numerous, sessile, on a flat 

 band-like stem that remains enclosed in a leaf-sheath. Perianth none. Male 

 flowers consisting of a single 1-celled anther. Female flowers of a single carpel, 

 with a bifid slender style. Ovule solitary. Fruit a nut. 



A genus of few species, found in most regions in shallow, salt, and brackish 

 water. 



Leaf notched at the end ... ... ... ... 1. Z. nana. 



Leaf entire, and rounded at the end ... ... . . 2. Z. tasmanica. 



1. Z. NANA, Moth. Rootstock creeping in the mud, with leafy branches at 

 intervals. Branches sub-erect. Leaves alternate, grass-like, with sheathing- 

 bases, often 1-2 feet long and about 1 line broad, usually with a single, distinct, 

 central nerve, and blunt-ended with a broad notch, but variable. Flowering leaf 

 with a sheath above the leaf-sheath, usually under 1 inch long, but variabl 

 Flower-stem contained in the sheath, the margins rather incurved, and some- 

 times with a partial membrane over the flowers, but not constant. Z. marina, 

 Hook. " Fl. Tas." ; Z. muelleri, Irm. 



Common on the coast ; also in Victoria, South Australia, New South "Wales, 

 and Queensland. Fl. summer. 



The plant differs from the Z. nana of the Northern Hemisphere, but not 

 sufficiently to be considered a d^tinct species. 



2. Z. TASMANICA, Mart. Similar in habit to the last, only the leaves rather 

 broader, rounded at the end, or sometimes with a narrow notch, and generally 

 with 3 or 5 parallel veins. Flowering sheath about 1 inch long. Z. muelleri, 

 Hook. " Fl. Tas." 



Southport, Derwent, and probably common in many parts ; also in Victoria 

 and South Australia. Fl. Dec-Jan. 



The plant is referred to as distinct from the last in most works, but I 

 have been unable to sort out all forms as distinctly one or the other. 



6. OTMODOCBA. 



Flowers unisexual, each solitary, within a sheathing bract. Perianth none. 

 Male flowers of 2 sessile 2-celled anthers. Female flowers of 2 distinct carpels, 

 each tapering into a slender bilobed style, each bearing 1 ovule. Fruit a small 

 nut. 



The genus' is small, but has a wide distribution in the Northern Hemisphere. 



