The Genus Pinus Part 11

Plate XVII.

Fig. 160, Cone. Fig. 161, Leaf-fascicle. Fig. 162, Magnified leaf-section.

23. PINUS CANARIENSIS

1825 P. canariensis Smith in Buch, Canar. Ins. 159.

Spring-shoots uninodal, pruinose. Bud-scales with conspicuously long free fimbriate margins. Leaves in fascicles of 3, the sheath persistent, from 20 to 30 cm. long; the hypoderm often in large ma.s.ses, the resin-ducts external, the endoderm with thin outer walls. Cones from 10 to 17 cm. long, short-pedunculate, ovoid-conic; apophyses l.u.s.trous or subl.u.s.trous nut-brown, more or less pyramidal, the umbo unarmed; seeds as in the last species.

A species confined to the Canary Islands, but cultivated in northern Italy. The stately habit of this tree is seen in Schroter's portrait (Exc. Canar. Ins. t. 15).

Plate XVII.

Fig. 163, Cone and seed. Fig. 164, Magnified leaf-section. Fig. 165, Habit of the tree.

[Ill.u.s.tration: PLATE XVII. P. LONGIFOLIA (160-162), CANARIENSIS (163-165)]

=IX. PINEAE=

Seed-wing articulate, short, ineffective. Leaves binate, the sheath persistent. One species only.

24. PINUS PINEA

1753 P. pinea Linnaeus, Sp. Pl. 1000.

1778 P. sativa Lamarck, Fl. Franc. ii. 200.

1854 P. maderiensis Tenore in Ann. Sci. Nat. ser. 4, ii. 379.

Spring-shoots uninodal. Leaves from 12 to 20 cm. long; resin-ducts external. Conelet mutic, slightly larger in the second year. Cones triennial, from 10 to 14 cm. long, ovoid or subglobose; apophyses l.u.s.trous nut-brown, convex, of large size, the umbo double; seeds large with a short, loosely articulated, deciduous wing.

A species of the Mediterranean Basin, from Portugal to Syria. Its northern limit is in southern France and northern Italy, but it is cultivated in the southern parts of the British Isles and is a familiar ornament of park and garden in southern Europe, and is valued for its peculiar beauty and for its large savory nuts. In wood anatomy as well as in the seed it agrees with the Gerardianae of the Soft Pines.

Plate XVIII.

Fig. 166, Fruit of three seasons. Fig. 167, Cone-scales and seed.

Fig. 168, Magnified leaf-section. Fig. 169, Habit of the tree.

[Ill.u.s.tration: PLATE XVIII. PINUS PINEA]

=Pinaster=

Bases of the bracts subtending leaf-fascicles decurrent. Seeds with an effective articulate wing. Umbo of the cone-scales dorsal. Leaves serrulate, stomatiferous on all faces, the sheath persistent. Walls of the tracheids of the medullary rays dentate.

Forty-two of the sixty-six species of Pinus are included in this subsection. As a group they are clearly circ.u.mscribed by several correlated characters and are more closely interrelated than the twenty-four species previously described. The distinctions of umbo and seed have disappeared. The umbo here is invariably dorsal, the seed-wing invariably articulate.

New forms, however, are gradually evolved--the seed with a thick wing-blade, the indurated oblique cone, the serotinous cone with its intermittent seed-release, and the multinodal spring-shoot. There are, moreover, new forms of leaf-hypoderm and a new position of the resin-duct.

Of these new characters, the thick wing-blade attains such proportions in the three species of the Macrocarpae that they can be grouped apart. But the characters that finally culminate in a lateral oblique serotinous cone are so gradually and irregularly developed that they offer no divisional distinctions. With the aid of wood and leaf characters, however, groups can be established which preserve the evolutionary sequence and, at the same time, the obvious affinity of the species.

Wing-blade thin or slightly thickened at the base.

Cones dehiscent at maturity.

Pits of the ray-cells large X. Lariciones Pits of the ray-cells small XI. Australes Cones serotinous, pits of the ray-cells small XII. Insignes Wing-blade very thick XIII. Macrocarpae

The species of this subsection are very difficult, if not impossible, to cla.s.sify by the usual method, which groups all species under a few characters a.s.sumed to be invariable and of fundamental importance.

Such a method can be successfully applied to the Soft Pines and to some of the Hard Pines, but cannot be applied to all the Hard Pines without forcing some of them into unnatural a.s.sociations.

To take an example, the group Pseudostrobus, characterized by pentamerous leaf-fascicles, appears in many systems. In this group are placed P. Torreyana and P. leiophylla. Another group, with trimerous fascicles, contains P. Sabiniana and P. taeda. Now there are no two species more obviously related by important peculiarities than P.

Torreyana and P. Sabiniana; nevertheless they are, by this method, kept apart and a.s.sociated with species which they resemble in no important particular.

An attempt is made here to avoid such incongruities. Groups X, XI and XII represent different stages of evolution. In the Lariciones the cone is symmetrical, and dehiscent and deciduous at maturity, while the spring-shoot is uninodal. In the Australes there is a similar cone, but the spring-shoot gradually becomes multinodal. In the Insignes the cone is oblique, persistent and serotinous, and the spring-shoot is multinodal.

These definitions state the degree of evolution attained by each group, but not all the species of a group conform exactly with its definition. In each group are species with a characteristic of another group. Among the Lariciones are a few species with both symmetrical and oblique cones, and two with persistent cones. Similar exceptions occur among the Australes. Among the Insignes are a few species with symmetrical cones, and two with cones that are rarely, if ever, serotinous.

There is, however, no difficulty in fixing the systematic position of these exceptional species through other characters which show their true affinity. They are placed with the species which they most resemble. Their exceptional characters are merely the evidence of the evolution that pervades and unites the groups. Therefore the definition of a group is not necessarily the exact definition of its species, and a species is placed in a group because all its characters, specific and evolutional, show a closer affinity with that group than with the species of any other.

=X. LARICIONES=

Pits of the ray-cells large. Cells of the leaf-hypoderm uniform.

Spring-shoots uninodal. Cones dehiscent at maturity.

This group represents the first stage in the evolution of the Hard Pines. All the species, like the Soft Pines, are uninodal and the cones are dehiscent at maturity, but the trend toward the serotinous species is shown in the occasional appearance of the oblique cone as a varietal form of a few species, and in the persistent cone of the last two species of this group.

All the species of this group are of the Old World except P. resinosa and P. tropicalis. These two are the only American Pines combining large pits with dentate tracheids, and are the only American Hard Pines with external resin-ducts of the leaf.

Cones deciduous at maturity.

Cones ovate or ovate-conic.

Conelet with tuberculate or entire scales.

Resin-ducts external and medial 25. resinosa Resin-ducts septal and external 26. tropicalis Conelet with mucronate scales.

Resin-ducts mostly external.

Conelet pedunculate, erect.

Cone nut-brown 27. Ma.s.soniana Cone dull tawny yellow 28. densiflora Conelet pedunculate, reflexed 29. sylvestris Conelet subsessile, erect 30. montana Resin-ducts mostly medial.

Bark-formation late 31. luchuensis Bark-formation early.

Cone nut-brown 32. Thunbergii Cone l.u.s.trous tawny yellow 33. nigra Cones narrow cylindrical 34. Merkusii Cones tenaciously persistent.

Leaves stout, relatively short 35. sinensis Leaves slender, relatively long 36. insularis

25. PINUS RESINOSA

1789 P. resinosa Aiton, Hort. Kew. iii. 367.

1810 P. rubra Michaux f. Hist. Arbr. Am. i. 45, t. 1.

Spring-shoots uninodal. Leaves binate, from 12 to 17 cm. long; resin-ducts external or external and medial; hypoderm uniform and inconspicuous. Scales of the conelet mutic. Cones from 4 to 6 cm. long, subsessile, symmetrical, deciduous the third year, leaving a few basal scales on the tree; apophyses subl.u.s.trous, nut-brown, somewhat thickened along a transverse keel.

From Nova Scotia and Lake St. John this species ranges westward to the Winnipeg River and southward into Minnesota, Michigan, northern New York and eastern Ma.s.sachusetts, with rare occurrence on the mountains of Pennsylvania. Under cultivation it is a beautiful tree, adapted to cold-temperate climates. It was considered by Loiseleur (1812) and by s.p.a.ch (1842) to be a variety of P. nigra (laricio). The two species vary in the color of the cone, the anatomy of the leaves, the buds, and in the armature of the conelet. A fallen cone of this species is moreover usually imperfect from the loss of a few basal scales.

Plate XIX.