Isodon (Plectranthus) effusus var. longitubus

For late autumn interest, very little touches this. Formerly Rabdosia, then Plectranthus(!) this Japanese woodlander reaches its peak in mid/late autumn when long tubed deep-purplish-blue flowers are formed en-masse in airy inflorescences at the top of 90cm stems. The bright green foliage develops very dark purple tints at flowering time. For shade or semi-shade, not too dry. Fully hardy.