SAXIFRAGE FAMILY SAXIFRAGACEAE
Mostly herbs but some species are bushes. The radially symmetrical flowers are on upright stalks in spikes, racemes or loose clusters and have 5 united sepals and 5 petals. The leaves are usually basal, often in rosettes, but when present, stem leaves are alternate.
SEDGE FAMILY CYPERACEAE
These grass-like or rush-like plants have no petals and the inconspicuous flowers are in small spikes in the leaf axils. The leaves are long, narrow and flat, and the solid stems are triangular. Sedges are found in moist or swampy ground.
SEDUM (ORPINE) FAMILY CRASSULACEAE
These low and often succulent plants have small radially symmetrical flowers in branching clusters. There are 4 or 5 sepals and 4 or 5 petals, but petals may be absent. The stamens may have prominent anthers. The simple, sessile leaves are often fleshy and may have a waxy surface.
SNAPDRAGON (FIGWORT) FAMILY SCROPHULARACEAE
The bilaterally symmetrical flowers have a stout corolla tube with upper and lower lips, 2 lobes above and 3 below. There are 4 or 5 stamens, some of which may lack anthers. The style may be forked. The leaves may be alternate, opposite or whorled and are simple or pinnately divided.
The genus Veronica has more or less radially symmetrical flowers with 4 petals, although the lowest is smaller than the other 3.
Digitalis, the first drug to be helpful in heart disease, is derived from leaves of plants in the Digitalis genus. Some species of snapdragon are poisonous. Mostly herbs, but one naturalized tree species (Princess tree).
SNOWBELL (STORAX) FAMILY STYRACACEAE
Mostly shrubs and small trees, indigenous to the tropics and relatively warm temperate zones, but occasionally found in Western Pennsylvania. The alternate leaves are simple, and may or may not be toothed. The flower corolla is tubular and usually white, and the fruit is a capsule with a single seed.
SOAPBERRY FAMILY SAPINDACEAE
A mostly tropical and subtropical family, locally represented by only 1 species, the Golden-rain tree, an occasional escape from cultivation. The leaves are alternate and pinnately compound, the leaflets toothed and/or lobed. The small, yellow, radially symmetrical flowers have 4 petals and are in branched clusters. The fruit is a papery capsule.
SPIDERWORT FAMILY COMMELINACEAE
The radially symmetrical flowers are in terminal clusters, and only 1 or 2 bloom at a time. There are 3 sepals and 3 roundish petals, and in the Dayflowers (Commelina genus) the lowest petal is smaller than the other 2. There are 6 stamens and the filaments may have colored hairs. The leaves are linear and parallel veined and the base forms a sheath partially surrounding the stem. The stem nodes are swollen.
SPURGE FAMILY EUPHORBIACEAE
The Euphorbia genus, or spurges proper, is the most important in our area, and its flowers are curious and distinctive. There are no sepals or petals, and what appear to be petals are really bracts, usually either 2 or 5 in number. In some individual flowers a stalked, nearly spherical pod protrudes from this cup of bracts. The flowers may be in umbels or clusters. The leaves are variable but may be whorled. The juice is milky.
Many spurges are poisonous, but useful products obtained from this family include rubber, tapioca, castor oil and tung oil. The poinsettia is a cultivated spurge.
ST. JOHNSWORT FAMILY GUTTIFERAE
The yellow or orange radially symmetrical flowers are in clusters. There are 5 petals and 5 sepals in Hypericum, the most important genus in our area. In Ascyrus, our only other genus, there are 4 petals and 4 sepals, and 2 of the sepals are much smaller than the other 2. The numerous stamens form a bushy center to the flower. The opposite, simple leaves are smooth edged and the margins of both leaves and petals are usually marked with dark or translucent dots.
STAFF-TREE FAMILY CELASTRACEAE
Shrubs, often vine-like and climbing, or trees. The alternate or opposite leaves are simple. The small, radially symmetrical flowers are single or in clusters. The calyx is 4 or 5 lobed and there are 4 or 5 petals. The fruit is a berry or capsule.
SYCAMORE FAMILY PLATANACEAE
This family is represented by only one genus (Platanus) in North America, and there is only 1 native species (P. occidentalis), a large tree with alternate, long-stalked, simple, palmately lobed leaves. The smooth bark peels in large thin flakes. The tiny flowers are clustered in long-stalked balls and the fruits are tufted nutlets, also crowded in hanging balls. The bark and fruit are distinctive.