Slender Speedwell 
A low growing, mat forming common perennial weed, which roots at the nodes on a slightly hairy creeping stem and can be present on many turf surfaces. It is also known as Round Leaved Speedwell. It has kidney shaped leaves, about 5mm in width, with very short hairs on the stem. Its leaves are darker green than Common Field Speedwell. It flowers during April to June, with blue-purple coloured flowers, with 4 petals, and with white tints in places to the petals, typically 8-12mm in diameter. Soil preference is more for a neutral soil pH, not especially acidic, moisture retentive soil, but not we
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Small-Leaved Weeds
A general term which is used for the finer and smaller leaf weeds, in contrast to larger and broader leaved ones. Examples include Clovers and Trefoils, Parsley Piert, Pearlwort, and Speedwells.
Smooth Hawksbeard
A common annual or short-lived perennial weed of turf surfaces. Its scientific name is Crepis capillaris. It has dandelion like leaves, but with narrow lobes projecting from the sides. The main flowering period is June to September, with small yellow flower heads, being about 10mm to 13mm in diameter. It is present on a wide range of soils.
Smooth Sow-thistle
A common annual weed of disturbed soils and newly sown areas, but not of well-maintained turf surfaces. Mowing a surface encourages the weed to develop a rosette adaptation, relatively low to the ground. Its leaves have shallow weak jagged edges, being grey-green in colour. It flowers from June to October, having yellow flower heads up to 25mm in diameter, but variable in size, although these would not normally be seen in a turf situation. It will grow in a range of soil conditions, from dry to moist, although preferring a more neutral, not acidic, soil pH, in open, not shaded, conditions. Its scientific name is Sonchus oleraceus.
Soleirolia soleirolii
The scientific name for the weed Mind Your Own Business.
Sonchus asper
The scientific name for the weed Prickly Sow-thistle.
Sonchus oleraceus
The scientific name for the weed Smooth Sow-thistle.
Spear Thistle
A common biennial weed of general amenity turf and neglected surfaces. Its scientific name is Cirsium vulgare. Its leaves are pinnately lobed, dull with many prickly hairs and with prominent spikes (the ‘spear') present on the leaf tip. It has a rough leaf surface, with pustules present. The stem is spiny and the plant develops a tap root. It flowers from July to September, with the flower heads typically having a diameter of about 25mm to 40mm, and being reddish-purple in colour. The flower heads are often single and with a very short smooth stalk, where present.
Speedwell
A common name for the large genus of Speedwell plants, whose scientific name is Veronica. At least five species might be found in turf surfaces:
1. Common Field Speedwell;
2. Germander Speedwell;
3. Slender Speedwell;
4. Thyme Leaved Speedwell;
5. Wall Speedwell.
Starweed