The Genus Pinus Part 5

1755 Pinus Duhamel, Traite des Arbres, ii. 121.

1790 Apinus Necker, Elem. Bot. iii. 269.

1852 Cembra Opiz, Seznam, 27.

1854 Strobus Opiz, Lotos, iv. 94.

1903 Caryopitys Small, Fl. Southeast. U. S. 29.

Leaves and shoots dimorphous, primary leaves on long shoots, secondary leaves on dwarf shoots. Flowers diclinous, the pistillate taking the place of long shoots, the staminate taking the place of dwarf shoots.

Growth of wood and fruit emanating from the nodes; buds, branchlets and cones, therefore, in verticillate a.s.sociation. Leaves and staminate flowers in internodal position, the primary leaves along the whole length of the internode, subtending secondary leaf-fascicles on the apical, staminate flowers on the basal part. Buds compounded of minute buds in the axils of bud-scales, becoming the bracts of the spring-shoot. Branchlets of one or more internodes, each internode in three parts--a length without leaves, a length bearing leaves and a node of buds. Cone requiring two, rarely three years to mature, displaying its annual growths by distinct areas on each scale. Seeds wingless or winged, edible and nutritious.

The Pines are confined to the northern hemisphere, but grow in all climates and under all conditions of soil, temperature and humidity where trees can grow. Some of the species are of very restricted range, but others are adaptable and can cover wide areas. The sixty-six species are distributed as follows--

Eastern Hemisphere, 23.

1 exclusively African (Canary Islands).

2 exclusively European.

3 about the Mediterranean Basin.

2 common to Europe and northern Asia.

14 exclusively Asiatic.

Western Hemisphere, 43.

28 in western North America, of which 12 are confined to Mexico and Central America.

15 in eastern North America, of which 2 are exclusively West Indian.

The two sections of the genus correspond with those of Koehne (Deutsch.

Dendrol. 28 [1893]) and his two names, Haploxylon and Diploxylon, are adopted here, together with his two subsections of Haploxylon, Cembra and Paracembra.

Of the two subsections of Diploxylon, Pinaster has been employed by Endlicher (Syn. Conif. 166 [1847]) and later authors for smaller or larger groups of Hard Pines. The subsection Parapinaster is now proposed.

The names of groups, Cembrae, Strobi, Cembroides, Gerardianae, Balfourianae, Pineae, Lariciones and Australes, are taken from Engelmann's Revision of the Genus Pinus (Trans. Acad. Sci. St. Louis, iv. 175-178 [1880]). The remainder, Flexiles, Leiophyllae, Longifoliae, Insignes and Macrocarpae, are here proposed.

In order to bring the ill.u.s.trations within the limits of the page the dimensions of cone and leaf, as shown on the plates, are a little smaller than life. In plates X and XXV the reproductions of the cones are reduced to 2/5 life-size.

SECTIONS, SUBSECTIONS, AND GROUPS

Bases of the fascicle-bracts non-decurrent A--HAPLOXYLON

Umbo of the cone-scale terminal a--Cembra

Seeds wingless.

Cones indehiscent I. Cembrae Cones dehiscent II. Flexiles Seed with an adnate wing III. Strobi

Umbo of the cone-scale dorsal b--Paracembra

Seeds wingless IV. Cembroides Seed-wing short, ineffective V. Gerardianae Seed-wing long, effective VI. Balfourianae

Bases of the fascicle-bracts decurrent B--DIPLOXYLON

Fascicle-sheath or seed of Haploxylon c--Parapinaster

Fascicle-sheath deciduous VII. Leiophyllae Fascicle-sheath persistent.

Seed-wing of the Strobi VIII. Longifoliae Seed-wing of the Gerardianae IX. Pineae

Fascicle-sheath persistent, seed-wing articulate, effective d--Pinaster

Base of wing-blade thin or slightly thickened.

Cones dehiscent at maturity.

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

HAPLOXYLON

Bases of the bracts subtending leaf-fascicles not decurrent. Staminate flowers not sufficiently developed in the bud to be apparent.

Spring-shoots uninodal. Fibro-vascular bundle of the leaf single. Cone symmetrical, of relatively fewer larger scales, its tissues softer.

Bark-formation late, the trunks of young trees smooth. Wood soft and with little resin, of uniform color and with relatively obscure definition of the annual rings. Tracheids of the medullary rays with smooth walls.

All the species of this section, except P. Nelsonii, have deciduous fascicle-sheaths. There are but two species of Diploxylon with deciduous sheaths, P. leiophylla and P. Lumholtzii, both of them easily recognized. The deciduous sheath, therefore, is an obvious and useful means for recognizing the Soft Pines. On the characters of the fruit and the wood Haploxylon can be divided into two subsections.

a. Cembra Umbo of the cone-scale terminal.

b. Paracembra Umbo of the cone-scale dorsal.

=Cembra=

Umbo of the cone-scale terminal. Scales of the conelet unarmed. Leaves in fascicles of 5, the sheath deciduous, the two dermal tissues distinct, the hypoderm-cells uniform. Pits of the cells of the wood-rays large.

Seeds wingless.

Cones indehiscent I. Cembrae.

Cones dehiscent II. Flexiles.

Seeds with an adnate wing III. Strobi.

=I. CEMBRAE=

Seeds wingless. Cones indehiscent, deciduous at maturity.

In this group of species there is no segregation of sclerenchyma into an effective tissue. The cones are inert under hygrometric changes and may always be recognized in herbaria by their persistent occlusion and soft tissues. The seeds are released only by the disintegration of the fallen cone. There is, however, a vicarious dissemination by predatory crows (genus Nucifraga) and rodents.

Leaves serrulate, their stomata ventral only.

Cones relatively larger, the apophyses protuberant 1. koraiensis.

Cones relatively smaller, the apophyses appressed 2. cembra.

Leaves entire, their stomata ventral and dorsal 3. albicaulis.

1. PINUS KORAIENSIS