Flowering of cool climate

Derrick Rooney1

The flowering and subsequent life offered for sale by a seed company in occasionally as Bambusa gracilis, cycles, if any, of the bamboos are not Thailand. The germination rate was which seems to be a portmanteau well studied in New Zealand, possibly listed as 70 per cent. Obviously it name used in some nurseries for because bamboos don’t flower here flowers in its native Chile also, several different bamboos. According very often, and when they do they because the in my garden was to (www.theplantlist.org), mostly die. raised from seed collected (not by me) which is maintained by the Royal in southern Chile. Botanic Gardens, Kew, and Missouri To get a handle on how seldom Botanical Garden, the real Bambusa bamboos flower in gardens, consider gracilis does not exist. The name is a the fact that in most of the the synonym for an attractive small, main morphological characters by somewhat frost tender which these are classified are correctly known as not based on the flowers and fruits, as falcatum. is usual, but on vegetative characters: stems, leaf-sheaths, leaf-blades, and Ten or more Phyllostachys, another so on. bamboo with several winter- hardy species, have been cultivated for many decades in New Zealand gardens, and as shelter belts for farms, orchards, or market gardens in the north, some of them probably since the 19th century. One of them is Phyllostachys edulis (Fig. 3A–B), the so-called edible bamboo whose fat growth buds are harvested in spring as bamboo shoots. This has been listed in New Zealand as P. heterocycla. A few Fig. 2 falconeri. of the other cultivated species are Photo: Clive Higgie, Paloma Gardens. recorded as naturalised in The elegant Himalayan bamboo, New Zealand, probably in most cases Himalayacalamus falconeri (Fig. 2), as a result of material discarded from flowers in cultivation every 19 to 25 gardens and shelter belts. Fully years, then dies after shedding seed. naturalised Phyllostachys include If some of the seeds germinate and P. aurea (the fishpole bamboo), survive the first winter, the species P. bambusoides (the giant timber Fig. 1 culeou. Photo: Clive Higgie, carries on. If not, it’s bye, bye, bamboo), and P. nigra var. nigra (black Paloma Gardens. bamboo. In 1998, this species bamboo; Fig. 4). flowered and died in gardens In the case of a South American forest throughout Canterbury, including my Until about 1998 the Allan Herbarium at bamboo, Chusquea culeou (Fig. 1), own. My specimen was 22 years old. Landcare Research, Lincoln, had no one of the few frost-hardy Southern Seedlings popped up like mustard and flowering specimens of P. nigra var. Hemisphere bamboos, there has cress all around the dead plant in the henonis (Fig. 5) collected in this never been an alternative means of following spring, but by the end of the country. I caused some consternation identification here. It has been 1999 winter none were left in my by presenting the staff with a four- cultivated in Britain and New Zealand garden other than a few seedlings I metre flowering stem from my plant. since the 19th century, but I’ve been had potted up and sheltered in a cold The same variety flowered at the same unable to find any record of its having frame. All these died in their second or time in another garden 30 kilometres flowered in either country during its third winter when they had grown too away, but P. nigra var. nigra itself, also 150-plus years in cultivation there. tall to be kept in the frame and had to growing in both gardens, did not, and However, there is a record of its live outside. This is clearly one of still has not flowered. having flowered decoratively and those plants that slowly gathers seeded in cultivation in the United Late in the 1998 autumn, after the seed hardiness as it ages. It is occasionally States (in a bamboo collection at of P. nigra var. henonis had shed and available from garden centres, usually North Plains, Oregon) in 2013. Seed the spent stems had browned off, I cut under the superseded name from this flowering was subsequently them down and grubbed out as much falconeri but of the stumps as I could.

1 PO Box 43, Hororata 7544, Canterbury, New Zealand; [email protected]

4 New Zealand Garden Journal, 2016, Vol. 19(1) A B Fig. 3 Phyllostachys edulis. A, grove showing the spectacular tall growth habit. B, close-up of stout canes which are technically called culms. Photos: Clive Higgie, Paloma Gardens.

Fig. 4 Phyllostachys nigra var. nigra. Photo: Clive Higgie, Fig. 5 Phyllostachys nigra var. henonis. Photo: Clive Higgie, Paloma Gardens. Paloma Gardens.

Two down, two to go. I planted I’d like to be able to say that I learned have excited taxonomists, but to a flowering shrubs and a smaller a lot from this rare event, but all it horticulturist they were almost a Phyllostachys species to fill the gap. really did was remind me of what I non-event. knew all along: that although the What were the odds against the An interesting and, as it happened, bamboos have woody stems and you replacement bamboo also flowering inconvenient, side effect occurred in have to look among the shrubs for and dying, within nine months and on the following summer. The grubbed- them in garden centres, they are the same site? Astronomical? But out Phyllostachys nigra var. henonis really just giant grasses, most that’s exactly what happened. made the greatest comeback since monocarpic (i.e., plants that flower, While all this was going on, a third Lazarus. Somewhere beneath the set seed and then die) but some not. Phyllostachys species, growing in an mass of dead crown and root stubs, Their life cycle makes them a sort of extra-large planter bag while I dormant buds sprouted fresh, green horticultural equivalent of a salmon. pondered a final site for it, also ran up shoots. I’d like, also, to be able to say that the to flower, and died. That solved the Clearly this is one of the minority of flowers were exciting, but there wasn’t problem of where to put it. None of bamboos that do not die after much to the few I have seen. If I the three had produced viable seed. flowering. These were vegetative, not hadn’t known what to look for I might Within 18 months, then, four bamboo flowering, stems. Their regrowth not have noticed them at all. They species had flowered in my garden. subsequently smothered the things I were inconspicuous; a bit like most This is more than most gardeners can had planted in its presumed gap. other grass flowers, really. They might expect to see in a lifetime.

New Zealand Garden Journal, 2016, Vol. 19(1) 5