Description
Petrophytum – Petrophyton – Rock Spirea –
There are about 3 to 5 species of low spreading, often mat forming subshrubs in this genus. They occur in screes or rock crevices in mountainous of Western North America. They are grown for their short, dense, spike like racemes of tiny, fluffy, cup shaped flowers, each with 5 overlapping petals, borne from early summer to autumn, and for their neat, compact habit. They form dense mats or mounds of short, prostrate, branching shoots with densely packed, smooth edged, inversely lance to spoon shaped blue gray to gray green, leathery, hairy leaves. Grow in crevices in a rock garden or scree planting, or in a tufa, or in a trough.
Grow in poor to moderately fertile, humus enriched, sharply drained, preferably slightly alkaline soil in full sun.
P. hendersonii – This dome forming subshrub from Northwestern USA grows 4″ tall and 8″ wide. From branched stems it carries hairy, spoon shaped, blue green leaves, to 3/4″ long. In summer, tiny, cup shaped white flowers are borne in dense, conical, spike like racemes, to 3″ long.
Zones 6-9
