76 THE YINK FAMILY. [Polyearpo*. 



A genus of two or three Mediterranean species, very near to Sper- 

 -gularia, but, in their minute petals and very short styles combined at the 

 base, showing a further approach to Ittecebraccce. 



1. P. tetraphyllum, Linn. (fig. 173). Four-leaved P. A glabrous, 

 much branched, spreading or prostrate annual, seldom more than 3 or 

 4 inches long. Leaves obovate or oblong, really opposite, but placed 

 as they usually are, under the forks, two pairs are so close together as 

 to assume the appearance of a whorl of 4. Flowers very small and 

 numerous, in loose,, terminal cymes ; the sepals barely a line long, 

 and rather concave. Petals much shorter, and very thin. Stamens 

 usually 3. 



In sandy situations, generally not far from the sea, in south-western 

 Europe, round the Mediterranean, along fche Atlantic, and as an intro- 

 duced weed over the world, perhaps indigenous in Australia. In 

 Britain, only in the Channel Islands and from Cornwall to Dorset. 

 Fl. summer. 



XIII. PORTULACE^. THE PURSLANE FAMILY. 

 More or less succulent herbs, with entire leaves, usually 

 opposite. Sepals 2 or rarely 3. Petals 5 or rarely more, 

 sometimes slightly united. Stamens either equal in number 

 and opposite to the petals, or indefinite. Styles 2 to 8, united 

 at the base. Capsule 1 -celled, with a free central placenta, and 

 several seeds with a curved embryo and mealy albumen, as in 

 Caryophyllacece. 



The family has a very wide geographical range, especially in North 

 and South America, with a few species dispersed over the other 

 quarters of the globe. It is nearly allied to the smaller species of 

 Caryophyllacece, and to the Illecebracece, but easily known by the calyx. 

 Several species belonging to the exotic genera Portidaca (Purslane] and 

 Calandrinia, as well as to Claytonia, are cultivated in our gardens. 



Petals 5, distinct. Stamens 5, opposite the petals .... 1. CLAYTONIA. 

 Petals united in a corolla, split open on one side. Stamens 3 . 2. MONIIA. 



I. CLAYTONIA. CLAYTONIA. 



Petals 5, free. Stamens 5, opposite to the petals and adhering to 

 them at the base. Stigmas 3. Capsule opening in 3 valves, and con- 

 taining 3 seeds. 



The genus comprises several species natives of North America or 

 northern Asia, and is only admissible into the British Flora amongst 

 naturalised aliens. 



1. C. perfoliata, Don (fig. 174). Perfdiate C. A glabrous, green, 

 somewhat succulent annual, with numerous spreading prostrate or 

 ascending stems, from a few inches to nearly a foot long. Radical 

 leaves on long petioles, small, broadly ovate or almost reniform. 

 Flowering stems with a single leaf below the flowers, nearly orbicular, 

 concave, and quite perfoliate, the stem passing through the centre, 

 evidently formed by the union of two opposite leaves. Flowers very 



