Senecio spiraeifolius developing flowerheads

The Senecio spiraeifolius flower stalks may be covered in cobwebby ridges of whitish woolliness as in the photo. The soft branches of the inflorescence vary from dark green to dull purple.

Flowerhead development is partly a performance of expanding floral components forcing protective coverings out of the way: The narrow, parallel bracts covering the green buds are gradually pushed apart by the burgeoning florets inside. Lengthening of the budding florets first breaks the bract tips central hold on top, when they are suddenly reduced to only long enough for covering the sides of the head.

Then the ray florets elongate fast from their in-curving position in the number two flowerhead in picture, spreading around the exposed disc and bending back as mature female florets. The outer ring of disc florets has already opened in the oldest head of the cluster in picture, the stamens taller than the five lobes of each floret. Disc florets are bisexual, rays female in Senecio.

When the flowerhead fades and fruiting begins, the cylindrical green involucre starts a new movement, bending inwards at the top, becoming a conic section that misses its tip. This is the last protective service performed by the involucre, holding all together before the ripe fruits are released.

Then the wind grasps the hairy attachment conveniently present at one end of each fruit, following its release from involucral bondage (Manning and Goldblatt, 1997; iNaturalist).