Over the summer, the spike grew at a truly impressive rate, with an average growth of 10cm/day until it reached a height of 4.5m (at one point we thought that we might have to remove some of the glass to allow it to continue its growth however, fortunately, it stopped just short of the ceiling).
The genus Agave belongs to the Asparagus family, Asparagaceae, and the flower stem, or ‘mast’, bore a strong resemblance to an asparagus spear until the flower branches started to show. While the Garden’s records indicate that this plant was present in the Botanic Garden in 1962, we did not know what species of agave it was. Now that it has flowered, our Assistant Curator, Dr Ángela Cano, has identified it as Agave vivipara, though this will not be properly confirmed until it produces fruits. This species originates in Mexico and the Southern USA.
Dr Cano explains: “The bottom section of the flower structure, or inflorescence, has started to flower, however its flowers may not look as pretty as people might expect as there aren’t any coloured petals. In the wild, pollinators are attracted by the massive inflorescence, the yellow colour of the stamens, the smell of the flowers (broccoli-like) and the abudnant nectar they produce.”
This flower has both male and female parts which should allow it to self-pollinate, though we believe that it may also be pollinated by birds in the wild. The stamen are long, yellow ‘sticks’ (filaments), which end with pollen covered anthers, these are the male part of the flower. There are six of these on each flower, with one shorter ‘stick’ without pollen which is the female part, or style. At the tip of the style is the stigma where the pollen will land. If this is Agave vivipara then the seedlings will start growing in the flower structure itself, Dr Cano continues: “That’s why the species is called vivipara, which means that it bears its own babies like mammals.”
Agaves are generally referred to as ‘century plants’ as they can take up to 100 years to flower. As a result, this is a rare sight in cultivation, combined with the fact they are not commonly grown in gardens. We think that it will flower for about a month (we’re not totally sure as the species is not fully identified), during which time the flowers will open from the bottom to the top. Once the plant has finished flowering, it will die.
The agave can be found in the Arid Lands House of the Glasshouse Range.
The species Agave comes from the desert regions of Mexico. They build up a large rosette of succulent leaves over many years and then put all their energy into producing an enormous flowering structure, or inflorescence. Agaves flower once and then die, so in order to continue the next generation, they produce copious amounts of seed, or sometimes new plants called bulbils, on the flowering structure.
The last time we had an agave flowering in the Garden was June 2004. This was Agave tequiliana (which is the plant that tequila comes from). There was also a flowering in 2001 of an Agave sisalana which went through the roof of the Glasshouse.
There are about 250 Agave species, many of which have a variety of commercial uses. Agave sap is used to make agave syrup as well as tequila, which comes from Agave tequiliana; Agave sisalana is widely cultivated for sisal, a fibre harvested from the leaves, which is used for making rope.
The Garden is open to visitors until 6pm in September and the Arid Lands House where the agave is growing will close at 5.30pm