Plant Tissue Culture PPT

In the early hours of morning, before gentle breezes awaken summer flowers, an unknown tuft of bright yellow catches my attention. Balancing camera and tripod, I step between plants, responding to an invitation to witness the wondrous emergence of a flower from a straw-coloured, intricately designed flower bud. This was my first introduction to the Armenian basket flower (Centaurea macrocephala), an event I will not forget; I felt I had been summoned that early summer morning.

What I had first perceived to be a flower bud was in fact the container for hundreds of individual flowers or florets. I also later learned that, in botanical terminology, it is called an involucre. Globose in shape, it is composed of hundreds of overlapping bracts, each a soft brown colour, paper-textured and almost translucent. This "bud" seemed in its own right a beautiful work of art.

Hemmed in by heavy-set neighbours, and almost forgotten, the tap-rooted, drought-tolerant plant had struggled through. It now stood as sturdy as its competitors, sporting an inflorescence with a funny spiky hairstyle of brilliant yellow. Later the plant was rescued and replanted in a spacious, full-sun position the following year. It prospered to a healthy clump of flowers, one to two metres (3 to 6 ft.) high, shooting up new stems when I cut the older ones back to the base at the end of fall.

Only one day of sunshine, after my first sighting, the intricate involucre had opened to a radiant, slightly fragrant orb, providing a perfect landing pad for visiting butterflies and bees. Four or five days passed before its yellow florets tired, flattening to threads of gleaming gold. The faded, straw textured remains took on a strikingly similar appearance to that of a toupee.

Then the real action began. This toupee looking cap lifted up and closed down again as the summer's day progressed to cooler temperatures. I watched the comical behaviour with curiosity, not closely enough, however. When my back was turned, it was thrown to the ground, leaving behind the involucre, which now resembled a finely crafted basket, a sculpted receptacle for the seeds, or achenes. Expansion and contraction of the involucre continued well into the fall, with the bracts opening during the daytime in their basket form and then closing back to their original globe shape in the evening. Centaurea macrocephala certainly deserves its common name of Armenian basket flower. Other non-scientific names, at times misleading, but so inviting, include yellow hardhat, great golden knapweed, golden thistle and lemon fluff.

When I encounter the unexpected in my garden, as I did with this engaging flower one summer's day, I am enlightened of what is integral to enjoyment as gardeners. These sudden surprises that delight and entertain us compensate for our endless bouts of weeding, deadheading and other chores. Tedium quickly evaporates in the face of such phenomena as a shrub flowering out of season; the recovery or reappearance somewhere else of a plant deemed dead, or, as in this instance, a new mysterious tuft of colour in the distance.

Originating in the grassy areas of the Caucasus Mountains, Armenian basket flower is hardy to zone 3. Drought-resistant, pest-resistant and almost indestructible, it is a good choice for hard-to-reach areas of the garden. Plant it in the back of the herbaceous border or where plants must compete with the roots of trees. Use the finished flowers for interesting dried-flowers. There's a further surprise in store for you when you see the dried flowers open to their basket shape in the heat of the house and then close to a globe shape outside!

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