Mycena acicula Schaeff.—This is one of the very small mycenas, and with the brilliant red pileus and yellow gills and stem it makes a very pretty object growing on leaves, twigs, or rotten wood in the forest. It occurs during summer and autumn. It is 2–5 cm. high, the cap 2–4 mm. broad, and the stem is thread-like.

The pileus is very thin, membranaceous, bell-shaped, then convex, when the pointed apex appears as a small umbo. It is smooth, striate on the margin, and of a rich vermilion or orange color. The gills are rounded at the stem and adnexed, rather broad in the middle, distant, yellow, the edge white, or sometimes the gills are entirely white. The stem is very slender, with a root-like process entering the rotten wood, smooth except the hairs on the root-like process, yellow.

Figure 100 is from plants (No. 2780, C. U. herbarium) collected in a woods near Ithaca. It has been found here several times.

Mycena cyanothrix Atkinson.—This is a very pretty plant growing on rotting wood in clusters, often two or three joined at the base, the base of the stem inserted in the rotten wood for 1–2 cm., and the base is clothed with blue, hair-like threads. The plants are 6–9 cm. high, the cap 1–2 cm. broad, and the stem not quite 2 mm. in diameter.

The pileus is ovate to convex, viscid when young. The color is bright blue when young, becoming pale and whitish in age, with a tendency to fuscous on the center. The cap is smooth and the margin finely striate. After the plants have dried the color is nearly uniform ochraceous or tawny. The gills are close, free, narrow, white, then grayish white, the edge finely toothed or fimbriate. The spores are globose, smooth, 6–9 µ. The stem is slender, hollow, faintly purple when young, becoming whitish or flesh color, flexuous, or nearly straight, even, often two united at the base into a root-like extension which enters the rotten wood. The base of the stem is covered with deep blue mycelium which retains its color in age, but disappears on drying after a time. Figure 101 is from plants (No. 2382, C. U. herbarium) collected at Ithaca, in woods, June 16, 1898.

Mycena hæmatopa Pers.—This is one of the species of Mycena with a red juice which exudes in drops where wounds occur on the plant. It is easily recognized by its dense cespitose habit, the deep blood red juice, the hollow stem, and the crenate or denticulate sterile margin of the cap. Numbers of the plant occur usually in a single cluster, and their bases are closely joined and hairy. The stems are more or less ascending according to the position of the plant on the wood. The plants are 5–10 cm. high, the cap is 1–2.5 cm. broad, and the stem 2–3 mm. in thickness.

The pileus is conic, then bell-shaped, and as the margin of the cap expands more appears umbonate, obtuse, smooth, even or somewhat striate on the margin. The color varies from whitish to flesh color, or dull red, and appears more or less saturated with a red juice. The thin margin extends a short distance beyond the ends of the gills, and the margin is then beautifully crenate. The gills are adnate, and often extend down on the stem a short distance by a little tooth. The stem is firm, sometimes smooth, sometimes with minute hairs, at the base with long hairs, hollow, in color the same as that of the pileus.

The color varies somewhat, being darker in some plants than in others. In some plants the juice is more abundant and they bleed profusely when wounded, while in other cases there is but little of the juice, sometimes wounds only showing a change in color to a deep red without any free drops exuding. Figure 102 is from plants collected at Ithaca, in August, 1899. It is widely distributed in Europe and North America.

Mycena succosa Pk., another species of Mycena with a juice, occurs on very rotten wood in the woods. It is a small plant, dull white at first, but soon spotted with black, and turning black in handling or where bruised, and when dried. Wounds exude a "serum-like juice," and the wounds soon become black. It was described by Peck under Collybia in the 25th Report, p. 74.

OMPHALIA Fr.

The genus Omphalia is closely related to Mycena and Collybia. It differs from these mainly in the decurrent gills. In the small species of Mycena where the gills are slightly decurrent, the pileus is not umbilicate as it is in corresponding species of Omphalia. In some of the species of Omphalia the pileus is not umbilicate, but here the gills are plainly decurrent. The stem is cartilaginous.

Omphalia campanella Batsch.—One of the most common and widely distributed species of the genus is the little bell-omphalia, Omphalia campanella. It occurs throughout the summer and autumn on dead or rotten logs, stumps, branches, etc., in woods. It is often clustered, large numbers covering a considerable surface of the decaying log. It is 1–3 cm. high, the cap 8–20 mm. broad, and the stem very slender.

The pileus is convex, umbilicate, faintly striate, dull reddish yellow, in damp weather with a watery appearance. The gills are narrow, yellow, connected by veins, strongly curved because of the form of the pileus, and then being decurrent on the stem. The stem is slender, often ascending, brownish hairy toward the base, and paler above.

Omphalia epichysium Pers.—This plant occurs during the autumn in woods, growing usually on much decayed wood, or sometimes apparently on the ground. The smoky, or dull gray color of the entire plant, the depressed or funnel-shaped pileus, and short, slender stem serve to distinguish it. The cap is 2–4 cm. broad, the plant is 3–5 cm. high, and the stem 2–4 mm. in thickness.

The pileus is convex, becoming expanded, umbilicate or depressed at the center or nearly funnel-shaped, smooth, smoky or gray with a saturated watery appearance, light gray or nearly white when dry. The gills are narrow, crowded, or a little decurrent. The slender stem is smooth, hollow, equal. Figure 104 is from plants (No. 3373, C. U. herbarium) collected in woods near Ithaca, N. Y., in the autumn of 1899.

PLEUROTUS Fr.

The genus Pleurotus is usually recognized without difficulty among the fleshy, white-spored agarics, because of the eccentric (not quite in the center of the pileus) or lateral stem, or by the pileus being attached at one side in a more or less shelving position, or in some species where the upper side of the pileus lies directly against the wood on which the plant is growing, and is then said to be resupinate. The gills are either decurrent (extending downward) on the stem, or in some species they are rounded or notched at the junction with the stem. There is no annulus, though sometimes a veil, and the genus resembles both Tricholoma and Clitocybe, except for the position of the stem on the pileus. In Tricholoma and Clitocybe the stem is usually attached at the center, and the majority of the species grow on the ground, while the species of Pleurotus are especially characterized by growing on wood. Some species, at least, appear to grow from the ground, as in Pleurotus petaloides, which is sometimes found growing on buried roots or portions of decayed stumps which no longer show above ground. On the other hand species of Clitocybe, as in C. candida (Fig. 91), often have an eccentric stem. This presents to us one of the many difficulties which students, especially beginners, of this group of fungi meet, and also suggests how unsatisfactory any arrangement of genera as yet proposed is.

Pleurotus ulmarius Bull. Edible.—The elm pleurotus is so called because it is often found growing on dead elm branches or trunks, or from wounds in living trees, but it is not confined to the elm. It is a large species, easily distinguished from the oyster agaric and the other related species by its long stem attached usually near the center of the cap, and by the gills being rounded or notched at their inner extremity. The cap is 5–12 cm. broad, the stem 5–10 cm. long, and 1–2 cm. in thickness.

The pileus is convex, the margin incurved, then nearly expanded, smooth, firm, white or whitish, or with shades of yellow or brown on the center, and the flesh is white. The gills are broad, rather distant, sinuate, white or nearly so. The spores are globose, 5–8 µ in diameter. The stem is firm, eccentric, usually curved because of its lateral attachment on the side of the tree, and the horizontal position of the pileus.

The elm pleurotus has been long known as an edible fungus, and is regarded as an excellent one for food on account of its flavor and because of its large size. It occurs abundantly during the late autumn, and at this season of the year is usually well protected from the attacks of insects. It occurs in the woods, or fields, more frequently on dead trees. On shade trees which have been severely pruned, and are nearly or quite dead, it sometimes appears at the wounds, where limbs have been removed, in great abundance. In the plants shown in Fig. 105 the stems are strongly curved because the weight of the cap bore the plant downward. Sometimes when the plant is growing directly on the upper side of a branch or log, the stem may be central.

Pleurotus ostreatus Jacq. Edible.—This plant is known as the oyster agaric, because the form of the plant sometimes suggests the outline of an oyster shell, as is seen in Fig. 107. It grows on dead trunks and branches, usually in crowded clusters, the caps often overlapping or imbricated. It is large, measuring 8–20 cm. or more broad.

The pileus is elongated and attached at one side by being sessile, or it is narrowed into a very short stem. It is broadest at the outer extremity, where it becomes quite thin toward the margin. It is more or less curved in outline as seen from the side, being depressed usually on the upper side near the point of attachment, and toward the margin convex and the margin incurved. The color is white, light gray, buff or dark gray, often becoming yellowish on drying. The gills are white, broad, not much crowded, and run down on the stem in long elevated lines resembling veins, which anastomose often in a reticulate fashion. The spores are white, oblong, 7–10 µ long. The stem when present is very short, and often hairy at the base.

The oyster agaric has long been known as an edible mushroom, but it is not ranked among the best, because, like most Pleuroti, it is rather tough, especially in age. It is well to select young plants. Figure 107 is from plants (No. 2097, C. U. herbarium) collected at Ithaca, N. Y.

Pleurotus sapidus Kalchb. Edible.—This plant usually grows in large clusters from dead trunks or branches or from dead portions of living trees. It grows on a number of different kinds of trees. The stems are often joined at the base, but sometimes the plants are scattered over a portion of the branch or trunk. The cap is from 5–10 cm. broad. The plants occur from June to November.

The pileus is convex, the margin incurved when young, and more or less depressed in age, smooth, broadened toward the margin and tapering into the short stem, which is very short in some cases and elongated in others. Often the caps are quite irregular and the margin wavy, especially when old. It is quite firm, but the margin splits quite readily on being handled. The color varies greatly, white, yellowish, gray, or brownish and lilac tints. The flesh is white. The stems are usually attached to the pileus, at or near one edge. The gills are white, broad, not at all crowded, and extend down on the stem as in the oyster agaric. They are white or whitish, and as in the other related species are sometimes cracked, due probably to the tension brought to bear because of the expanding pileus. The spores are tinged with lilac when seen in mass, as when caught on paper. The color seems to be intensified after the spores have lain on the paper for a day or two.

It is very difficult to distinguish this species from the oyster agaric. The color of the spores seems to be the only distinguishing character, and this may not be constant. Peck suggests that it may only be a variety of the oyster agaric. I have found the plant growing from a dead spot on the base of a living oak tree. There was for several years a drive near this tree, and the wheels of vehicles cut into the roots of the tree on this side, and probably so injured it as to kill a portion and give this fungus and another one (Polystictus pergamenus) a start, and later they have slowly encroached on the side of the tree.

Figure 108 represents the plant (No. 3307, C. U. herbarium) from a dead maple trunk in a woods near Ithaca, collected during the autumn of 1899. This plant compares favorably with the oyster agaric as an edible one. Neither of these plants preserve as well as the elm pleurotus.

Pleurotus dryinus Pers. Edible.—Pleurotus dryinus represents a section of the genus in which the species are provided with a veil when young, but which disappears as the pileus expands. This species has been long known in Europe on trunks of oak, ash, willow, etc., and occurs there from September to October. It was collected near Ithaca, N. Y., in a beech woods along Six-mile creek, on October 24th, 1898, growing from a decayed knothole in the trunk of a living hickory tree, and again in a few days from a decayed stump. The pileus varies from 5–10 cm. broad, and the lateral or eccentric stem is 2–12 cm. long by 1–2 cm. in thickness, the length of the stem depending on the depth of the insertion of the stem in a hollow portion of the trunk. The plant is white or whitish, and the substance is quite firm, drying quite hard.

The pileus is convex to expanded, more or less depressed in the center, the margin involute, and the surface at first floccose, becoming in age floccose scaly, since the surface breaks up into triangular scales more prominent in and near the center, smaller and inconspicuous toward the margin. The prevailing color is white, but in age the scales become cream color or buff (in European plants said to become fuscous). The pileus is either definitely lateral (Fig. 109) or eccentric when the stem is attached near the center as in Fig. 110. The gills are white, becoming tinged with yellow in age, decurrent (running down on the stem) in striæ for short distances, 4–5 mm. broad, not crowded. The stem is nearly central (Fig. 110), or definitely lateral (Fig. 109), the length varying according to conditions as stated above. It is firm, tough, fibrous. The veil is prominent in young and medium plants, floccose, tearing irregularly as the pileus expands.

Figure 110 is from plants (No. 2478a C. U. herbarium) growing from knothole in living hickory tree, and Fig. 109 from plants (No. 2478b) growing on a dead stump, near Ithaca.

According to the descriptions of P. dryinus as given by Persoon, and as followed by Fries and most later writers, the pileus is definitely lateral, and more or less dimidiate, while in P. corticatus Fr., the pileus is entire and the stem rather long and eccentric. Stevenson suggests (p. 166) that corticatus is perhaps too closely allied to dryinus. The plants in our Fig. 110 agree in all respects with P. corticatus, except that possibly the lamellæ do not anastomose on the stem as they are said to in corticatus. According to the usual descriptions corticatus is given as the larger species, while Fig. 109 of our plant, possessing the typical characters of dryinus, is the larger. The form of the pileus, the length and position of the stem, depends, as we know, to a large extent on the position of the plant on the tree. When growing from the upper side, so that there is room above for the expansion of the cap, the pileus is apt to be more regular, just as is the case in Pleurotus ulmarius, and the stem more nearly central. When the plant grows from a hollow place in the trunk as those shown in Fig. 110 did, then there is an opportunity for them to grow more or less erect, at least until they emerge from the hollow, and then the pileus is more nearly equal in its expansion and the stem is longer. Berkeley describes specimens of P. dryinus with long stems growing from a hollow in an ash, and Stevenson (p. 167) reports the same condition.

Pleurotus sulfureoides Pk.—This rare species, first collected in the Catskill Mountains 1869, and described by Peck in the 23rd Report, N. Y. State Mus., p. 86, 1870, was found by me on two different occasions at Ithaca, N. Y., during the autumn of 1898, on rotting logs, Ithaca Flats, and again in Enfield Gorge, six miles from Ithaca. The plants are from 5–8 cm. high, the cap 3–5 cm. broad, and the stem 5–7 mm. in thickness, and the entire plant is of a dull, or pale, yellow.

The pileus is nearly regular, fleshy, thin toward the margin, convex, umbonate, smooth or with a few small scales. The gills are rather crowded, broad, rounded or notched at the stem, pale yellow. The spores are elliptical, 7–9 × 5–6 µ. The stem is ascending and curved, nearly or quite central in some specimens in its attachment to the pileus, whitish or yellowish, mealy or slightly tomentose at the apex.

Figure 111 is from plants (No. 2953, C. U. herbarium) on rotting log, Ithaca Flats, October, 1898.

Pleurotus petaloides Bull. Edible.—The petal-like agaric is so called from the fancied resemblance of the plant to the petal of a flower. The plant usually grows in a nearly upright or more or less ascending position, or when it grows from the side of a trunk it is somewhat shelving. It is somewhat spathulate in form, i. e., broad at the free end and tapering downward into the short stem in a wedge-shaped manner, and varies from 2–10 cm. long and 1–5 cm. in breadth. It grows on fallen branches or trunks, on stumps, and often apparently from the ground, but in reality from underground roots or buried portions of decayed stumps, etc.

The pileus varies from a regular wedge-shape to spathulate, or more or less irregularly petaloid, or conchoid forms, the extremes of size and form being shown in Figs. 112, 113. The margin is at first involute, finally fully expanded, and the upper surface is nearly plane or somewhat depressed. The color is often a pale reddish brown, or brown, and sometimes pure white. The margin is sometimes marked with fine striations when moist. The upper portion near the union with the stem is sometimes tomentose, sometimes smooth. The gills are narrow, white, or yellowish, crowded and strongly decurrent. While the plant varies greatly in form and size, it is easily recognized by the presence of numerous short whitish cystidia in the hymenium, which bristle over the surface of the hymenium and under a pocket lens present a "fuzzy" appearance to the lamellæ. They are 70–80 × 10–12 µ. The spores are white.

Figures 112, 113 are from plants collected at Ithaca.

Pleurotus serotinus Schrad. This is an interesting plant and occurs during the autumn on dead trunks, branches, etc., in the woods. The stem is wanting, and the cap is shelving, dimidiate, reniform or suborbicular. The plants occur singly or are clustered and overlapping, about the same size and position as Claudopus nidulans, from which it is readily told by its white gills and spores. The color varies from dull yellow to brownish, often with shades of olive or green.

Pleurotus applicatus Batsch.—This is a pretty little species and usually occurs on much decayed wood, lying close to the ground so that it is usually directly on the under side of the log or branch. It does occur, however, on the side of the log when it is more or less shelving, because of the tendency of the pileus always to be more or less horizontal.

The pileus is 4–6 mm. broad, its upper surface closely applied to the wood or bark on which it is growing when it appears directly on the under side. The margin is sometimes free and involute. Sometimes it is attached only by the center of the pileus. There is then often a short process. When it grows on the side of the log it is attached laterally, or on the upper side of one margin, while the greater portion of the pileus is free and shelving. The surface is smooth or somewhat hairy. The color varies from gray to dark bluish gray, or black with a bluish tinge. The gills are thick, broad in proportion to the size of the cap, distant, and are said by some to be paler than the pileus. In plants collected at Ithaca, the gills are often as dark as the pileus. The entire plant is rather tough, and revives after being dried if placed in water, resembling in this respect Marasmius, Panus, or Trogia, and it may be more nearly related to one of these. Figure 114 is from plants (No. 4599, C. U. herbarium) collected at Ithaca.

HYGROPHORUS Fries.

The genus Hygrophorus is one which presents some difficulties in the case of some of the species, especially to beginners, and plants need to be studied in the fresh condition to understand the most important character which separates it from certain of the other white-spored agarics. The substance of the pileus is continuous with that of the stem, that is, the stem is not easily separated from the cap at the point of junction, but is more or less tenacious. The gills may be adnexed, adnate, sinuate, or decurrent, but what is important they are usually rather distant, the edge is acute or sharp, and gradually thickened toward the junction with the cap, so that a section of the gill is more or less triangular. This is brought about by the fact that the substance of the cap extends downward into the gill between the laminæ or surfaces of the gill. But the most important character for determining the genus is the fact that the surfaces of the gills become rather of a waxy consistency at maturity, so that they appear to be full of a watery substance though they do not bleed, and the surface of the gill can be rather easily removed, leaving the projecting line of the trama. This is more marked in some species than in others. The waxy consistency of the gills then, with the gills acute at the edge, broad at the point of attachment to the pileus, and the gills being rather widely separated are the important characters in determining the species which belong to this genus. The nearest related genus is Cantharellus, which, however, has blunt and forked gills. A number of the plants are brilliantly colored.

Hygrophorus chrysodon (Batsch.) Fries. Edible.—This plant has about the same range as Hygrophorus eburneus, though it is said to be rare. It is a very pretty plant and one quite easily recognised because of the uniform white ground color of the entire plant when fresh, and the numerous golden floccules or squamules scattered over the cap and the stem. The name chrysodon means golden tooth, and refers to these numerous golden flecks on the plant. A form of the plant, variety leucodon, is said to occur in which these granules are white. The plant is 4–7 cm. high, the cap 4–7 cm. broad, and the stem 6–10 mm. in thickness. The plants grow on the ground in the woods, or rather open places, during late summer and autumn.

The pileus is convex, then expanded, the margin strongly involute when young, and unrolling as the cap expands, very viscid, so that particles of dirt and portions of leaves, etc., cling to it in drying. The golden or light yellow granules on the surface are rather numerous near the margin of the pileus, but are scattered over the entire surface. On the margin they sometimes stand in concentric rows close together. The gills are white, distant, decurrent, 3–6 mm. broad, white, somewhat yellowish in age and in drying, and connected by veins. The spores white, oval to ovate, the longer ones approaching elliptical, 6–10 × 5–6 µ.

The stem is soft, spongy within, nearly equal, white, the yellowish granules scattered over the surface, but more numerous toward the apex, where they are often arranged in the form of a ring. When the plant is young these yellow granules or squamules on the stem and the upper surface of the inrolled margin of the pileus meet, forming a continuous layer in the form of a veil, which becomes spread out in the form of separated granules as the pileus expands, and no free collar is left on the stem.

Figure 115 is from plants (No. 3108, C. U. herbarium) collected in October, 1898, in woods, and by roadsides, Ithaca, N. Y.

Hygrophorus eburneus (Bulliard) Fries. Edible.—This plant is widely distributed in Europe and America. It is entirely white, of medium size, very viscid or glutinous, being entirely covered with a coating of gluten, which makes it very slippery in handling. The odor is mild and not unpleasant like that of a closely related species, H. cossus. The plants are 6–15 cm. high, the cap is from 3–8 cm. broad, and the stem 3–8 mm. in thickness. It grows on the ground in woods, or in open grassy places.

The pileus is fleshy, moderately thick, sometimes thin, convex to expanded, the margin uneven or sometimes wavy, smooth, and shining. When young the margin of the cap is incurved. The gills are strongly decurrent, distant, with vein-like elevations near the stem. Spores rather long, oval, 6–10 × 5–6 µ, granular. The stem varies in length, it is spongy to stuffed within, sometimes hollow and tapers below. The slime which envelops the plant is sometimes so abundant as to form a veil covering the entire plant and extending across from the margin of the cap to the stem, covering the gills. As the plant dries this disappears, and does not leave an annulus on the stem.

Figure 116 is from a photograph of plants (No. 2534, C. U. herbarium) collected in Enfield Gorge near Ithaca, N. Y., Nov. 5th, 1898.

Hygrophorus fuligineus Frost. Edible.—The smoky hygrophorus was described in the 35th Report of the N. Y. State Museum, p. 134. It is an American plant, and was first collected at West Albany, during the month of November. It is one of the largest species of the genus, and grows on the ground in woods, in late autumn. The plants are 5–10 cm. high, the cap from 3–10 cm. broad, and the stem 1–2 cm. in thickness. The large size of the plant together with the smoky, brown, viscid cap aid in the recognition of the plant.

The pileus is convex, becoming expanded, smooth, very viscid, dull reddish brown or smoky brown, darker on the center; the margin of the pileus is even in young specimens, becoming irregular in others; and in age often elevated more or less. The gills are broad, distant, usually decurrent, often connected by veins, white, with yellowish tinge in drying. The spores oval to elliptical, 8–12 × 5–7 µ. The stem is stout, sometimes ascending, equal, or enlarged in the middle, or tapering toward the base, solid, viscid like the pileus, usually white, sometimes tinged with the same color as pileus, somewhat yellowish tinged in drying.

Figure 117 is from plants (No. 2546, C. U. herbarium) collected in Enfield Gorge near Ithaca, Nov. 5, 1898.

Hygrophorus pratensis (Pers.) Fr. Edible.—This hygrophorus grows on the ground in pastures, old fields, or in waste places, or in thin and open woods, from mid-summer to late autumn. The plants are 3–5 cm. high, the cap 2–5 cm. or more broad, and the stem 6–12 mm. in thickness. The cap being thick at the center, and the stem being usually stouter at the apex, often gives to the plant a shape like that of a top.

The pileus is hemispherical, then convex, then nearly or quite expanded, white, or with various shades of yellow or tawny, or buff, not viscid, often cracking in dry weather. Flesh very thick at the center, thinner at the margin. The flesh is firm and white. The gills are stout, distant, long decurrent, white or yellowish, and arcuate when the margin of the pileus is incurved in the young state, then ascending as the pileus takes the shape of an inverted cone. The gills are connected across the interspaces by vein-like folds, or elevations. The spores are nearly globose to ovate or nearly elliptical, white, 6–8 × 5–6 µ. The stem is smooth, firm outside and spongy within, tapering downward.

Hygrophorus miniatus Fr. The vermilion hygrophorus is a very common plant in the woods during the summer. The cap and stem are bright red, sometimes vermilion. The gills are yellow and often tinged with red. The gills are adnate or sinuate. The plant is a small one but often abundant, and measures from 3–5 cm. high, and the cap 2–4 cm. broad. Hygrophorus coccineus (Schaeff.) Fr., is a somewhat larger plant and with a scarlet cap, which becomes yellowish in age, and the gills are adnate. Hygrophorus conicus (Scop.) Fr., is another bright red plant with a remarkable conical pileus, and the gills are annexed to free.

Hygrophorus psittacinus Fr., is a remarkably pretty plant, the cap being from bell-shaped to expanded, umbilicate, striate, and covered with a greenish slime. It occurs in woods and open places. The prevailing color is yellow, tinged with green, but it varies greatly, sometimes yellow, red, white, etc., but nearly always is marked by the presence of the greenish slime, the color of this disappearing as the plant dries. It occurs in pastures, open woods, etc., from mid-summer to autumn.

Hygrophorus hypothejus Fr., is another very variable plant in color as well as in size, varying from yellow, orange, reddish, sometimes paler, usually first grayish when covered with the olive colored slime. The gills are decurrent, white, then yellow. It occurs in autumn.

LACTARIUS Fr.

The genus Lactarius is easily distinguished from nearly all the other agarics by the presence of a milky or colored juice which exudes from wounded, cut, or broken places on the fresh plant. There are a few of the species of the genus Mycena which exude a watery or colored juice where wounded, but these are easily told from Lactarius because of their small size, more slender habit, and bell-shaped cap. By careful observation of these characters it is quite an easy matter to tell whether or not the plant at hand is a Lactarius. In addition to the presence of this juice or milk as it is commonly termed, the entire plant while firm is quite brittle, especially the gills. There are groups of rounded or vesiculose cells intermingled with thread-like cells in the substance of the cap. This latter character can only be seen on examination with the microscope. The brittleness of the plant as well as the presence of these groups of vesiculose cells is shared by the genus Russula, which is at once separated from Lactarius by the absence of a juice which exudes in drops.

In determining the species it is a very important thing to know the taste of the juice or of the fresh plant, whether it is peppery, or bitter, or mild, that is, tasteless. If one is careful not to swallow any of the juice or flesh of the plant no harm results from tasting any of the plants, provided they are not tasted too often during a short time, beyond the unpleasant sensation resulting from tasting some of the very "hot" kinds. It is important also to know the color of the milk when it first exudes from wounds and if it changes color on exposure to the air. These tests of the plant should be made of course while it is fresh. The spores are white, globose or nearly so in all species, and usually covered with minute spiny processes. There are a large number of species. Peck, 38th Report, N. Y. State Mus., pp. 111–133, describes 40 American species.

Lactarius volemus Fr. Edible.—This species is by some termed the orange brown lactarius because of its usual color. It was probably termed Lactarius volemus because of the voluminous quantity of milk which exudes where the plant is broken or bruised, though it is not the only species having this character. In fresh, young plants, a mere crack or bruise will set loose quantities of the milky juice which drops rapidly from the plant. The plant is about the size of Lactarius deliciosus and occurs in damp woods, where it grows in considerable abundance from July to September, several usually growing near each other. The pileus is convex, then expanded, often with a small elevation (umbo) at the center, or sometimes plane, and when old a little depressed in the center, smooth or somewhat wrinkled. The cap is dull orange or tawny, the shade of color being lighter in some plants and darker in others. The flesh is white and quite firm. The gills are white, often tinged with the same color as the pileus, but much lighter; they are adnate or slightly decurrent. The stem is usually short, but varies from 3–10 × 1–2 cm. It is colored like the pileus, but a lighter shade.

The milk is white, abundant, mild, not unpleasant to the taste, but sticky as it dries. This plant has also long been known as one of the excellent mushrooms for food both in Europe and America. Peck states that there are several plants which resemble Lactarius volemus in color and in the milk, but that no harm could come from eating them. There is one with a more reddish brown pileus, Lactarius rufus, found sparingly in the woods, but which has a very peppery taste. It is said by some to be poisonous.

Lactarius corrugis Pk. Edible.—This species occurs with Lactarius volemus and very closely resembles it, but it is of a darker color, and the pileus is more often marked by prominent wrinkles, from which character the plant has derived its specific name. It is perhaps a little stouter plant than L. volemus, and with a thicker cap. The surface of the pileus seems to be covered with a very fine velvety tomentum which glistens as the cap is turned in the light. The gills are much darker than in L. volemus. The plants are usually clearly separated on account of these characters, yet there are occasionally light colored forms of L. corrugis which are difficult to distinguish from dark forms of L. volemus, and this fact has aroused the suspicion that corrugis is only a form of volemus.

The milk is very abundant and in every respect agrees with that of L. volemus. I do not know that any one has tested L. corrugis for food. But since it is so closely related to L. volemus I tested it during the summer of 1899 in the North Carolina mountains. I consider it excellent. The methods of cooking there were rather primitive. It was sliced and fried with butter and salt. It should be well cooked, for when not well done the partially raw taste is not pleasant. The plant was very abundant in the woods, and for three weeks an abundance was served twice a day for a table of twelve persons. The only disagreeable feature about it is the sticky character of the milk, which adheres in quantity to the hands and becomes black. This makes the preparation of the plant for the broiler a rather unpleasant task.

Figure 118 is from plants (No. 3910, C. U. herbarium) collected in the woods at Blowing Rock, during September, 1899. Just before the exposure was made to get the photograph several of the plants were wounded with a pin to cause the drops of milk to exude, as is well shown in the illustration.

The dark color of the lamellæ in L. corrugis is due to the number of brown cystidia or setæ, in the hymenium, which project above the surface of the gills, and they are especially abundant on the edge of the gills. These setæ are long fusoid, 80–120 × 10–12 µ. The variations in the color of the gills, in some plants the gills being much darker than in others, is due to the variations either in the number of these setæ or to the variation in their color. Where the cystidia are fewer in number or are lighter in color the lamellæ are lighter colored. Typical forms of Lactarius volemus have similar setæ, but they are very pale in color and not so abundant over the surface of the gills. In the darker forms of L. volemus the setæ are more abundant and darker in color, approaching those found in L. corrugis. These facts, supported by the variation in the color of the pileus in the two species and the variations in the rugosities of the pileus, seem to indicate that the two species are very closely related.