Mistaken identities

Sunday, 07 March 2010

Brillantaisia subulugarica

Two plants in my garden at the moment are often taken to be Salvia specimens, but they actually belong to quite separate genera, despite their similarity to many of the Salvia I grow. The first is Brillantaisia subulugarica, which I bought with a label proclaiming it to be 'giant blue sage'. However, it is not even in the same general Lamiaceae family as the Salvia, belonging instead to the Acanthaceae, which includes plants such as Justicia species, Acanthus mollis, Rhinacanthus and Ruellia. Brillantaisia is an imposing soft-wooded shrub from tropical Africa, growing up to 3m tall in summer, bedecked with spires of intriguing hooked blue-purple flowers. It is in bloom for about six months and makes a bold statement in a semi-tropical style border along with plants such as Salvia, Canna, Dahlia and Amaranthus. The leaves are large and lush green, adding to its tropical appearance.

Brillantaisia subulugarica

Mine grows in full sun, but other gardeners tell me that theirs grow and flower in shade just as well. It copes with very ordinary garden conditions. I have never been able to find a single reference to it in any of my gardening books, though it is listed on internet sites. Thanks to its ease of propagation, it has spread throughout the Sydney gardening fraternity. I cut mine back to within 60cm of the ground in late August and this seems to help it form a shrubbier shape.

Lepechinia salviae

Another plant often mistaken for a Salvia that is in bloom now is Lepechinia salviae. It has large, grey-green textured leaves, shaped like arrowheads; they have a sharp medicinal - though not unpleasant - scent. From late February to May it sends up long spires of burgundy flowers, held in dark calyces on deep pinkish stems. Like Brillantaisia, it is a shrubby perennial, and one that is almost impossible to find in any reference book. Mine grows to about 1.5m tall and I cut it back hard at the end of winter, when new growth appears at the base. From what little I have been able to find out about it, it possibly originates in Chile and, like Salvia, is a member of the broad Lamiaceae family of plants. There are other species: I have grown Lepechinia hastata in the past, a winter-flowering version, which I did not like as much as L. salviae.

Lepechinia salviae with Iresine herbstii cultivar and Salvia guaranitica Large Form

It looks at home grown among Salvia specimens (especially blue-flowered ones) and other denizens of a semi-tropical border. I have mine growing nearby a very dark purple-brown form of Iresine herbstii, which echoes the dark calyces of the Lepechinia blooms. I grow Brillantaisia behind it and this forms a long-lasting composition through late summer and autumn. I grow my specimen in sun, with reasonable soil, but I think they could survive a poorer position.

Agastache cultivar in the garden of Jill Budden, Springwood NSW

Another Salvia look-alike which I have seen growing recently is Agastache. There are a few different cultivars sold in the nurseries these days, and with their spires of tubular flowers, they do look very like a Salvia, and also belong to the Lamiaceae family of plants. Some originate in North America, where they are pollinated by hummingbirds, giving rise to a common name of 'hummingbird mint'. Some I have seen are a pretty apricot one (Agastache aurantiacus, ht 90cm) and a taller one with dusky pink flowers (Agastache mexicana, ht 120cm). They are said to like dry, sunny spots so could be a good choice for places where other plants fail to thrive, so I plan to try them one day.

It is sometimes hard to come by such unusual plants these days, but one fabulous opportunity to find plant treasures is at the Collectors' Plant Fair at Bilpin, coming up on 17 and 18 April.