Order 1. Araucariaceæ. This order most frequently has solitary ovules, turned downwards and attached to the centre of the cone-scales. In Agathis (Dammara) the arrangement is the most simple, a winged seed (Fig. [265]), which hangs freely downwards, being borne in the centre of the undivided cone-scale. In Araucaria, the stamens with the free, pendulous pollen-sacs have been represented in Fig. [242]; the ovuliferous scale is united for nearly its whole length with the bract, and projects from its apex in the shape of a sheath-like, dentate scale, resembling the ligule in Isoëtes, and may therefore be termed a “ligule.” Araucaria (S. America, Australia) has often rather broad leaves (A. brasiliensis). The ovuliferous scale in Cunninghamia is more distinct, and stretches transversely over the entire cover-scale; it bears three inverted ovules (Fig. [266]) (Eastern Asia).
Fig. 265.—Agathis (Dammara) australis. Cone-scale with the seed. A Longitudinal section; A’ from within; fv, fv’ vascular bundles; v wing.
Fig. [266].—Cunninghamia sinensis. Cone-scale with three ovules, interior view: d cover-scale; f ovuliferous scale.
Fig. 267.—A-G Pseudotsuga douglasii: A cone, B cone-scale, with the inner side turned forward; the points of the cover-scale are seen behind it; C-G transitions from the acicular leaf to the cover scale, from the base of a ♀ cone. H Pinus montana. Young ovuliferous scale, with the inner side turned forward; the ovules are now in the stage for pollination. J-M Abies alba: J male cone; b bud-scale; a anthers; K L M individual anthers.—Pinus montana: N pollen-grain; the two lateral expansions are the air-bladders; in the upper part of the interior of the grain a vegetative cell may be seen, and in the centre the large cell-nucleus.
Dammara-resin, which is used for varnish, is obtained from Agathis (Dammara) species (New Zealand, Philippine Islands).
Order 2. Abietaceæ (Pine and Fir Trees). The leaves are spirally arranged and needle-like. The flowers are monœcious. The male flowers are long, and catkin-like, with numerous stamens, each bearing two oblong pollen-sacs. The pollen-grains are most frequently tri-lobed, having two bladder-like appendages, formed as outgrowths of the exospore, to assist in their distribution by the wind (Fig. [267] N). The bracts are arranged spirally. The union between the bract and the ovuliferous scale, which is found in the preceding order, is not in this instance so complete; these scales make their appearance as two free parts, and are attached only at their bases (Fig. [268]); the lower portion, that is the cover-scale, in most instances remains quite small (Fir, Red Pine, and others), it is only in the “Noble Pine” (Abies) and Pseudotsuga douglasii, that it attains a greater length than the ovuliferous scale (Fig. [267], B-G). On the other hand the upper part, the ovuliferous scale (the vascular bundles of which have the bast turned upwards), grows strongly and elongates, especially after fertilisation, becoming woody or leathery; it is commonly termed the “cone-scale,” but is in reality only homologous with a part of the “cone-scale” in the other order of Pinoideæ. On the side of the ovuliferous scale, turned towards the axis, are situated two ovules with micropyles directed inwards. The seeds are most frequently provided with a false wing (a tissue-like part of the surface of the ovuliferous scale). Cotyledons, more than 2, verticillate. Fertilisation does not take place until some time after pollination. In Pinus, for instance, the pollen-tube only penetrates the nucellus for a short distance during the year of pollination, and then ceases its further growth, fertilisation not taking place until after the middle of the next year; whilst the seeds ripen about a year and a half after pollination. In the Larch and others, the seeds are mature in the autumn succeeding pollination.
Fig. 268.—A Abies: c the cover-scale; s ovuliferous scale, or “cone-scale”; sk ovules in a young condition. B Pinus: ovuliferous scale with two ovules (s); m the two-lobed micropyle; c “mucro”; b the cover-scale behind. C Abies: ripe “cone-scale” with two seeds (sa); f wing of seed.