Small ferns having clusters of fronds with slender dark stalks. Fronds triangular or 5-sided in outline, undersides covered with white or yellow waxy powder. Sori appear black in mature fronds, in contrast to the light colored waxy particles. Sori follow the very small veinlets, but are so crowded that their forked or pinnate arrangement is obscured and the underside of each pinna appears to have one large confluent sorus. No indusium is present. Although about 15 species of this genus are known in the world, mostly in tropical areas, only one species with several varieties, all found in California, occur in the United States.

KEY TO THE SPECIES:

Fronds dark green above, golden yellow beneath when young P. triangularis
Fronds white above and beneath, and white on stalks var. pallida

GOLD FERN

Pityrogramma triangularis (Kaulf.) Maxon (Fig. 34)

Gymnogramme triangularis

Fronds 3 to 12 inches high, easily recognized by its triangular shape, dark green color above and waxy golden yellow underneath on young fronds. As fronds mature most of the underside is covered with black sporangia, as shown in the illustration.

Gold Back Fern and Stamp Fern are other common names for this fern. An attractive golden print results when the underside of a young frond is pressed upon dark cloth or paper. This species, states Barrett and Gifford, was chewed for toothache by California Indians, care being taken to keep the quid near the troublesome tooth.

The Gold Fern is one of our more common ferns throughout the whole foothill area of the Sierra Nevada up to 4,500 feet elevation, and in the Coast Range. It occurs in damp places in sun or shade, in soil or cracks of rocky ledges. As the soil dries out, the fronds curl and die. The plants remain dormant until the next rainy season when they produce new fronds. This species is found from Lower California to Alaska, and in Idaho and Arizona.

WHITE FERN

Pityrogramma triangularis (Kaulf.) Maxon var. pallida Weatherby (Fig. 35, 36)

A rare variety, closely resembling the preceding species, but distinguished by the whitish, waxy granules covering upper and lower leaf surfaces and also the stalk. As with the Gold Fern, the lower surface is gradually obscured by the dark sporangia which develop over the veins and cover much of the lower leaf surface. However, the underlying color of the top of the leaf in the White Fern is always a pale green, never dark green as in the preceding species.

This plant is occasionally found in the Sierra foothills below Sequoia and Kings Canyon National Parks, in Mariposa and Tuolumne Counties, and has been reported from Butte County. It is found in Yosemite near Arch Rock, but usually occurs at lower elevations.

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Fig. 34 GOLD FERN (Pityrogramma triangularis). Upper: Found in soil where moisture is available during the winter and spring months. Lower: Details of lower side of one frond when black sporangia cover most of the gold waxy particles.

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Fig. 35 WHITE FERN (Pityrogramma triangularis var. pallida). Growing under granite boulders which form a cave. These ferns never grow in direct sunlight, although this variety may occur in more open places. White waxy material covers the stalks and both upper and lower surfaces of the fronds.

Fig. 36 WHITE FERN (Pityrogramma triangularis var. pallida)

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Fig. 36 Left: WHITE FERN (Pityrogramma triangularis var. pallida). Lower side of one frond with young sporangia partially obscuring the white waxy material.

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