The Viscum seeds deposited here by some fruit eating Little Karoo bird are already developing tiny green roots, aiming for penetrating the bark of the host branch. The seeds may belong to the parasite, Viscum rotundifolium, the prospective host shrub in picture being Lycium pumilum.
The connecting part, the haustorium, is the modified stem or root grown by the parasitic invader that penetrates the host plant stem tissues sufficiently for accessing the host’s juices, absorbing its nutrients and water. If any one of these little green roots succeeds, the branch will bear a persistent passenger until the host or parasite dies.
The haustorium allows the parasite to grow and bear flowers and fruits of its own, subsidised by the host plant rooted in the ground (Van Rooyen and Van Rooyen, 2019; Vlok and Schutte-Vlok, 2015; iNaturalist).