sentences:  Siliceous mountains such as the Sistema Central, Serra da Estrela, the Sistema Ibérico of the region of Soria, and parts of the Cantabrian mountains, are covered by thickets of "Cytisus purgans" (variously known as "Andorra broom", "Provence broom", or "Spanish gold hardy broom") or Alpine juniper ("Juniperus communis" subsp.