x Abu Dhabi, UAESunday 23 July 2017

Nick's Garden: Agave deliver quiet drama along the Corniche

Spikes of bell-shaped flowers have dominated Abu Dhabi's Corniche in recent weeks.

Maybe it's because my conversations with friends and family in the UK have recently been peppered with talk of snow, floods, storms and icebergs (spotted off the northern coasts this winter), but my daily walks along Abu Dhabi's Corniche have been particularly cheered of late by the sight of so many plants and trees in flower. Horticulturally this is no surprise, but for somebody from Europe the impact of seeing the clashing pink, purple and orange bracts of Bougainvillea glabra and the hot yellow, orange and red panicles of caesalpinia pulcherrima in benevolent January sunshine is difficult to overestimate.

Although these colourful blooms most immediately vie for my attention, it's actually the quieter, architectural spires of succulent plants belonging to the family agavaceae that have really dominated Abu Dhabi's seafront in recent weeks. Of these, the most spectacular are the glorious, two-metre tall panicles of off-white, bell-shaped flowers that belong to the evergreen yucca but these have also been joined in my affections by the flower spikes of the various species of agave that are also planted along the route.

I'll go no further before making a confession: I'm unable to identify the particular species of yucca in question with 100 per cent confidence. In my defence I'd say that yucca can often be difficult to identify precisely because many plants that are commercially available are crosses or hybrids. For example, the plants that caught my eye have characteristics that could identify them as either yucca gloriosa (Spanish dagger) or yucca aloifolia (Spanish bayonet) and if pushed, I'd say they are the latter but I'm happy to stand corrected.

Both species originate in the south-eastern United States, are salt- and drought-tolerant and thrive in sandy soils, so perhaps it's not surprising that they also feature heavily in gardens and public landscapes where these factors are an issue. This also makes them particularly useful for UAE gardeners. However, as their common names suggest, the yucca is also armed with vicious spines that can pierce clothing and skin, so they need to be located with care away from pathways and in areas where they are unlikely to harm children and pets. As an accent plant or focal point in a low-water-demand xeriscape, however, yucca look particularly effective when planted alongside drifts of Aloe vera (whose yellow and coral pink flowers can also be seen at the moment) as well as their fellow family members the agave.

As with so many plants that are grown primarily for their structural and architectural qualities, agave are often planted as single specimens or as pot plants. However, I always believe that these desert dwellers benefit most from massed planting because this highlights the often subtle differences between species and maximises their visual impact. Of the several hundred members of the agave genus, those most commonly seen in the UAE include the giant century Plant (agave americana), the graceful dwarf agave desmettiana, and the elegant swan's neck agave (agave attenuata), the latter of which is named after the plant's tall, curving flowering stem that bears pale yellow and white flowers that complement the plant's glaucous-blue foliage.

Growing to a height of six metres at a speed of up to seven centimetres a day, the mast-like flowering stems of agave always fill me with wonder and sadness in equal measure. Depending on the species and growing conditions, agave can live for up to 25 years before a single flowering and seed setting, an event that represents the end of their life cycle. Fortunately this swansong is often accompanied by the production of new life in the form of juvenile offshoots that spread out from the plant's central rosette via underground rhizomes. For gardeners whose prize specimens fail to produce these "pups" (as they are known in the trade), a visit to the garden centre may soon be in order.

I once worked at a plant nursery in central London that proudly displayed a giant pair of two-metre-wide agave for more than 16 years that were simply too large and too expensive to move or to sell. They'd been cared for by the same gardener for that whole time and when both plants started to produce flower spikes within days of each other I remember he fought hard not to shed a tear.

The flowering spikes, which grew to an eventual height of more than four metres, attracted local journalists and parties of schoolchildren who came to see a plant that was literally growing and dying before their eyes. Blooming largely unnoticed along Abu Dhabi's Corniche, the inflorescences of agave desmettiana are quietly attracting a slightly different crowd of inquisitive warblers and iridescent purple sunbirds, all eager to taste the rich nectar afforded by this once in a lifetime opportunity.