A Remarkable Senecio Hybrid.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 60, 1930, Page 265

A Remarkable Senecio Hybrid. By H. H. Allan and W. A. Thompson. [Read before the Philosophical Institute of Canterbury, 1st August, 1928; received by Editor, 8th April, 1929; issued separately, 15th August, 1929.] Plates 28–29. Senecio southlandicus is a herb of tussock-grassland in the South Otago Botanical District, and S. Hectori is a large shrub of the forest in the North-western South Island Botanical District. The two therefore do not meet in nature, and considering their great disparity in habitat requirements and growth-forms one would hardly have expected that they would hybridize when brought together. But two Senecio plants that appeared spontaneously at Fern Tree House, Dunedin, show clearly by their characters that they arose from the crossing of the two species mentioned. In this garden plants of S. southlandicus were growing on a rockery in close proximity to a shrubbery containing a large specimen of S. Hectori. In 1915 there appeared under S. Hectori seedlings that were clearly referable to Senecio, but of a form hitherto unknown. One of these was transplanted to a dry place, the other into a rather damp, shady spot. As they grew up both showed an intermingling of the characters of the two parents, though this was more marked in the plant in the shady position. It is this plant that is here further described. The plant is now (May, 1928) some 71 cm. tall, and is of bushy habit. From a main stem 23 cm. high and 25 mm. diam. are given off a number of more or less decumbent branches, semi-woody towards the bases, and clothed with rather large leaves. These bear at the bases of the blades pinnules showing the presence of Hectori blood. The inflorescences are intermediate in degree of development between those of the two parents. Seed is set, but so far we have failed to germinate any. The plant grows readily from cuttings, and we have established several for further observation and report. It is obvious that the occurrence of hybrids between such dissimilar parents is of considerable importance. Further details are given in the following table:

Characters. S. southlandicus. Hybrid. S. Hectori. Growth-form. Herb; with resulate radical lvs. and stout rootstock Semi-woody plant; with numerous ascending branches Tall shrub; with numerous stout, spreading branches Leaves: petioles 2 to 12 cm., glandular pilose 5 to 18 cm., glabrate 2 to 3 cm., pilose blades 6 to 11., oblong to sub-rotund 12 to 22 cm., elliptic-oblong 15 to 30 cm., oblong-lanceolate tips obtuse or round obtuse to subacute acute bases rounded, cordate, or truncate somewhat rounded to truncate with several leaf-like pinnae gradually narrowed with several narrow pinnae margins entire, or with short distant teeth with frequent teeth with numerous acute teeth upper-surface glabrate or slightly silky glabrate, silky when young scaberulous lower-surface glabrate or slightly silky, often purplish white tomentose when young, glabrate and purplish when old clothed with white cottony tomentum Inflorescences: scapes sparingly branched, bearing 5 to 12 heads only much-branched, with spread of up to 20 cm. across very much branched, with spread of up to 30 cm. across bracts linear-oblong oblong-lanceolate linear-lanceolate involucral bracts pilose; linear, obtuse pilose; linear-oblong; subacute pubescent; lanceolate, acute Heads 1.3 to 4 cm. diam. 3 cm. diam. 2.5 to 5 cm. diam. Ray-florets luteous primrose yellow white achenes linear, glabrous linear, glabrous linear, glabrous pappus hairs slender, minutely scabrid slender, minutely scabrid rigid, scabrid.

Fig. 1.—Left—Leaf of Hybrid. Middle—Leaf of S. southlandicus. Right—Leaf of S. Hectori.

Fig. 2.—Hybrid Senecio, showing habit. Fig. 3.—Hybrid Senecio, showing inflorescence.