448 THE POLTGON^UM FAMILY. 



Sorrel D., and often turning red. Leaves all narrow-lanceolate and linear, 

 and some at least of every plant sagittate, the lobes of the base usually 

 spreading and often divided. Flowers small, dioecious, in slender terminfil 

 panicles. Segments of the perianth small, broadly ovate or orbicular, entire, 

 and thin ; the inner ones closing over the nut as in the other species, but 

 scarcely enlarged ; the outer ones erect, not reflexed as in the Sorrel D. 



In pastures, especially in dry open places, over the greater part of the 

 globe without the tropics, penetrating far into the Arctic regions, and as- 

 cending high upon alpine summits. Abundant in Britain. Fl.from spring 

 till autumn. 



II. OXVRZA. OXYRIA. 



A single species, with the habit of a small DocTc of the Sorrel group, 

 separated from that genus because the perianth has only 2 inner and 2 outer 

 segments of the perianth, and the ovary has only 2 stigmas. 



1. Kidney Oxyria. Oxyria renifonuis, Campd. 

 (Sumex digyrms, Eng. Bot. t. 910.) 



A glabrous perennial, seldom above 6 inches high, of an acid flavour. 

 Leaves chiefly radical, cordate-orbicular or kidney-shaped, usually less than 

 half an inch, but sometimes an inch broad. Stem slender and almost leaf- 

 less, terminating in a simple or slightly branched raceme. Flowers small, 

 in clusters of 2 or 3, on slender pedicels ; the inner segments of the peri- 

 anth slightly enlarged, but shorter than the nut. Stamens 6. Nut flat, 

 orbicular, about 2 lines in diameter, including a scarious wing, which 

 surrounds it, and is either entire or notched at the top and at the base. 



A high alpine plant, in all the great mountain -ranges of Europe and 

 central and Russian Asia, descending to a lower level in the north, and ex- 

 tending far into the Arctic regions. Frequent in the mountains of Scot- 

 land, northern England, North Wales, and northern Ireland. FL summer. 



ni. POLYGONUM. POLYGONTIM. 



Herbs, varying njuch in habit, but not so stiffly erect as the DocJcs, and 

 sometimes prostrate, floating, or twining ; the scarious stipules usually sheath- 

 ing the stem and often fringed at the edge ; the leaves alternate. Flowers 

 small, pale-green or red, clustered or rarely solitary in the axils of the upper 

 leaves, or in terminal heads, spikes, or panicles. Perianth of 5 (rarely fewer) 

 segments, either all equal or 2 or 3 outer ones enlarged. Stamens 8 or 

 sometimes fewer. Styles 3 or 2, sometimes united at the base, the stigmas 

 entire. Nut triangular or flattened, enclosed in or surrounded by the per- 

 sistent perianth. 



A large genus, widely spread over every part of the globe. 



Stems much branched, wiry, often prostrate. Flowers axillary. 



Annual. Nuts scarcely ahove a line long, opaque, dotted, or 



wrinkled 1. Knotioeed P. 



Perennial. Nuts about 2 Knes long, very smooth and shining . 2. Sea P. 

 Stems twining. Flowers in loose racemes. 



Fruiting perianth triangular, scarcely ^Tinged 3. CUmTnng P. 



Fruiting periautli with 3 white, scarious wings 4. Copse P. 



1 



