This time of the year, many of the statuesque plants we grow primarily for their foliage are also producing their flowers, a welcome secondary feature.
Perhaps the most striking of these is the multitude of host varieties now available. Depending on their background, many cultivars have attractive spikes of white or pale lavender flowers. In some cases, the flowers are thin and dainty, while other types – especially the blue-leaved forms – have more substantial blooms.
This peculiarity is not confined to exotic plants – the popular renga renga lily, Arthropodium cirratum, is in flower at the moment too with its lovely pure white flowers showing up on prominent stems.
The plant was widely distributed in the wild in Aotearoa in most areas north of Greymouth and Kaikōura. It was also cultivated by Māori. Missionary and botanist William Colenso said it was not of primary importance as a food crop but reported that the roots were cooked in a hangi before consumption.
He recorded that the plants found around old sites were larger than those from the wild. I know there was extensive planting at Orangokorero, an old pā site near Matakitaki-a-Kupe, Cape Palliser.
Although the flowers are very pretty, renga renga is usually grown in bulk for its foliage value. The slightly arching leaves with the hint of grey give the effect of a bed of hostas or similar, while the masses of relatively small flowers on prominent, although slender, stems at their best about now.
These stems reach about a metre high, each carrying large numbers of six-petaled flowers. The stamen are worth a closer look – they are tricoloured. Although mainly white, they also have purple tones and are tipped with gold.
Renga renga lilies are truly perennial, being clump-forming and growing to about 60 centimetres high and with similar girth. They make a great contrast to finer-leaved plants such as grasses and ferns and look their best when bulk-planted among other plants. They will provide cover in some areas where agapanthus might otherwise be considered. They are not as aggressive as agapanthus, and certainly more ecologically sound.
They prefer partial to full sun and will cope with quite dry and coastal sites. The ones growing at Orangikorero are in very well-drained soils and have partial shade. Unfortunately, renga renga are not fully hardy to frost. This winter’s frost certainly damaged some foliage, but most plants will quickly recover with new leaves.
Some years ago, I saw a trial of these superb native plants at the Auckland Botanic Garden [ABG] in Manukau. I was surprised at the variety of forms, some from wild collections while others were sourced in the nursery trade.
There was considerable variation in foliage colour, with some plants having almost no hint of the blue /green shade, while others were very glaucus. There was also a continuum of leaf width, some forms being very narrow, while there were many with extra wide leaves.
I was interested to see one of the trial subjects. ‘Pink Elite’ had relatively deep pink flowers, although they were sparsely carried. However, it seemed to be especially attractive to snails and slugs, as it was the variety with the worst damage.
One of the best-performing clumps was of ‘Matapouri Bay’. This is taller than most varieties and has relatively wide leaves. It is very popular in the nursery trade, but the ABG report said that this variety is quite variable, indicating that it may have been bulked up through seed propagation rather than vegetatively.
The trial plants had the flower spikes removed after blooming, and old leaves pruned which helps keep the plants looking tidy and attractive. Among the varieties ABG recommended were ‘Parnell’ and ‘Downtown’, both selected from plants growing in municipal plantings in Auckland. ‘White Knight’ performed well in the trials. It pays to remember that the trial was carried out in Auckland conditions and plants will perform differently in Wairarapa.
Other native herbaceous perennials include Euphorbia glauca, with its wonderful blue foliage and the startlingly attractive parataniwha, Elastema rugosum. The latter is a great foliage plant usually found in wet and shaded places, in gullies and alongside streams.
The leaves are unforgettable – green-purple to bronze, heavily textured and rough with serrated edges. The flowers are nothing to write home about – summer borne; they are small. This plant, which will grow to about 50cm high, doesn’t need any fancy cossetting, but does require a cool, damp place to flourish and will do best in reasonable shade. This is only found in the wild in the North Island, and has been reported from the Tararuas, although I have not seen it there. I did stumble across a large patch in the hills above Eastbourne – an exciting find – and saw a lovely clump at ABG.