The North American Slime-Moulds Part 47

_b._ Stipe long, slender.

1. Capillitium of dark, tapering, oft-united threads 3. _L. columbinum_

2. Capillitial threads rigid, dark brown, seldom united 4. _L. scintillans_

_B._ Peridium not blue, silvery.

_a._ Stipe long, slender.

1. Capillitium very intricate, forming a compact net 6. _L. arcyrionema_

2. Capillitium of rigid dark brown threads 1. _L. physaroides_

_b._ Stipe short, heads large, 1 mm. or more 2. _L. robustum_

1. LAMPRODERMA PHYSAROIDES (_Alb. & Schw._) _Rost._

1805. _Physarum physaroides_ Alb. & Schw., _Consp. Fung._, p, 103.

1875. _Lamproderma physaroides_ (Alb. & Schw.) Rost., _Mon._, p. 202.

Sporangia gregarious, wide-spreading, globose, the peridium persistent with a silver metallic, sometimes bra.s.sy, l.u.s.tre; stipe long, brown or black, tapering upward; hypothallus well developed, brown or purple, usually not continuous; columella swollen, obtuse, short at best, hardly attaining the centre of the sporangium; capillitium very rigid, of simple or sparingly branched, dark-brown threads radiating from the clavate apex of the columella and only here and there anastomosing toward the surface, the ultimate divisions distinctly rough; spores lilac brown, rough, 10-12.5 .

This species is well described and ill.u.s.trated in Rostafinski's _Monograph_. It is well marked by its clavate columella and peculiarly simple, dark rigid capillitium, the branches of which rise in great numbers immediately from the columella, and maintain their primitive thickness during the greater part of their length. The transverse vincula are often at right angles to the princ.i.p.al branches, and the meshes, where formed, are often long and rectangular. Externally, it resembles _L. arcyrionema_, but is by its spores and capillitium instantly distinguished. Rostafinski gives the spores 12.5-14.2 . Large spores are less common in the specimens before us. Lister figures a sessile variety.

In our first edition this species was entered from lists published for New England, New York, and Ohio. The intervening years, however, have brought no confirmation. Specimens from Maine and Ohio, with large spores, represent _L. columbinum_, and those cited for New York are forms of _L. violaceum_. It is accordingly doubtful that _L.

physaroides_ (A. & S.) Rost. occurs in North America. That it is to be found in Europe there seems no doubt. The figure and description by Schweinitz, _l. c._, may indeed be inconclusive, but Rostafinski's citation and abundant description leave no doubt as to his opinion; while numerous localities named would indicate adequate material. What Rostafinski described will no doubt obtain wider recognition some day.

2. LAMPRODERMA ROBUSTUM _Ell. & Evh._

1892. _Lamproderma robustum_ Ell. & Evh., Ma.s.s., _Mon._, p. 99.

1894. _Lamproderma violaceum_ var. _sauteri_ Rost., List., _Mycetozoa_, p. 129.

1899. _Lamproderma sauteri_ Rost., Macbr., _N. A. S._, p. 140.

Sporangia gregarious, globose, dull black, the peridium when present silvery, shining, or simply smooth, transparent and without iridescence, stipitate; stipe short, black, tapering rapidly upward, annulate with the persisting base of the peridium; columella short, thick, truncate, and widened at the top; hypothallus well developed, brown or purple; capillitium dense, made up of dark brown branches, numerous and rather slender, repeatedly branched and anastomosing toward the surface to form a slight delicate network with abundant free ends; spores dark purple brown, rough, 14-16 .

This species in outward appearance resembles _L. physaroides_, from which it is easily distinguished by the much greater diameter of the globose sporangium, 1 mm. or more. The persistent base of the peridium is also characteristic, very prominent sometimes, and visible to the naked eye. The capillitium is also unlike that of _L. physaroides_; resembles more nearly that of _L. violaceum_. From the latter species _L. robustum_ is distinguished by the color of the peridium, and by the larger, darker spores and generally different capillitium. In our former edition this is called _L. sauteri_ Rost. That much-quoted author distinguished _L. violaceum_ and _L. sauteri_; the English authors make the last named a variety only of the former. This our American species is _not_.

It is, as presented in our western mountains, clear-cut, well defined, not a variety of anything. The original name is therefore restored.

_Lamproderma arcyrioides_ (Somm.) Morgan is probably a form of _L.

columbinum_. The original _L. arcyrioides_ has not yet been certainly identified in North America; see following species.

Colorado, Oregon, Washington, California.

3. LAMPRODERMA COLUMBINUM (_Pers._) _Rost._

1796. _Physarum columbinum_ Pers., _Obs. Myc._, I., p. 5.

1875. _Lamproderma columbinum_ Rost., _Mon._, p. 203.

Sporangia scattered, gregarious; rich violet or purple with metallic iridescence, globose, stipitate; the stipe long, three-fourths the total height, slender, subulate, black; hypothallus scant, purplish or brown; columella small, one-third the height or less, tapering or acute, black; the capillitium brown throughout, not dense, arising from nearly all parts of the columella, freely branching and anastomosing to an open, large-meshed network; spore-ma.s.s black, spores by transmitted light dark brown, rough, 10-12 .

Rostafinski distinguished this beautiful species by the color of the peridium and the conic columella. According to Mr. Lister, Rostafinski was not specially careful in labelling his material, different forms having been included under this specific name. Nevertheless, the description is well drawn, and excludes _L. physaroides_ completely. At all events our American specimens correspond so well with the description of _L. columbinum_ (Pers.) Rost. that there seems no doubt that we have here what the Polish author figured and described, whether or not he was always consistent in applying his labels. The color distinguishes at sight the present species from _L. physaroides_, and the capillitium and large rough brown spores distinguish it from _L.

violaceum_. The capillitium of the minute _L. scintillans_ is much denser and more rigid, and the spores smaller. The stipe when dry is ciliate.

This is the common species of our western mountains, especially on the Pacific slope. In the Cascades every dark ravine is certain to show it in later summer and autumn, far extended colonies covering the moist surfaces of every mouldering log; the myriad globoid sporangia giving back when brought to the sunlight the most extravagant blues and greens with all the splendor of metallic sheen, their brilliant beauty never fails to quicken the attention of even the most insensate tourist.

Abundant in the western forests, in the east extremely rare; Maine, Pennsylvania, South Carolina, Washington, Oregon; Vancouver, Canada.

4. LAMPRODERMA SCINTILLANS (_Berk. & Br._) _Morg._

PLATE V., Figs. 2, 2 _a_.

1877. _Stemonitis scintillans_ Berk. & Br., _Jour. Linn. Soc._, XV., p. 2.

1877. _Lamproderma arcyrioides_, var. _iridea_ Cke., _Myx. G. B._, p. 50.

1892. _Lamproderma irideum_ (Cke.) Ma.s.s., _Mon._, p. 95.

1894. _Lamproderma scintillans_ (Berk. & Br.) Morg., _Jour. Cin.

Soc._, p. 47.

Sporangia gregarious, scattered, globose or depressed-globose, rich metallic blue or purple, iridescent, stipitate; the stipe long, slender, even, inclined and nodding or sometimes erect; hypothallus small, circular; columella cylindric, small, not reaching the centre, black; capillitium dense, of rigid, straight, sparingly branched or anastomosing, brown threads, which are sometimes white or colorless just as they leave the columella; spores globose, rough, violaceous brown, 8 .

This is _L. irideum_ of Cooke and of Ma.s.see's _Monograph_. Its capillitium is remarkable, and const.i.tutes an easy diagnostic mark. The threads appear at first sight entirely simple, but are really several times furcate, and not infrequently anastomose. The spores are covered with spa.r.s.ely sown large papillae, easily seen under moderate magnification.

This is one of our earliest species. To be sought in May on beds of decaying oak leaves in the woods, especially in wet places, near streams, etc.

Rare. New England, Pennsylvania, Ohio, Iowa.

5. LAMPRODERMA VIOLACEUM (_Fries_) _Rost._

1829. _Stemonitis violacea_ Fries, _Syst. Myc._, III., p. 162.

1875. _Lamproderma violaceum_ (Fries) _Rost., Mon._, p. 204.

Sporangia closely gregarious or scattered, depressed-globose, more or less umbilicate below, metallic blue or purple, sessile or short stipitate; stipe stout, dark brown or black, even; hypothallus, when the sporangia are crowded, a thin, continuous, purplish membrane; when the sporangia are scattered, the hypothallus discoidal; columella cylindric or tapering slightly upward, the apex obtuse, black, attaining the centre of the sporangium; capillitium lax and flaccid, made up of flexuous threads branching and anastomosing to form a network, open in the interior, more dense without, the threads at first pale brown as they leave the columella, becoming paler outward to the colorless tips; spores minutely warted, violaceous gray, 9-11 .

This is our most common species; found on decaying sticks and logs late in the fall. Its pale capillitium will usually distinguish it, especially where the sporangia are empty; then the pallid free extremities of the capillitial branches give to the little spheres under the lens a white or h.o.a.ry appearance not seen in any other species.

The plasmodium is at first almost transparent, then amber tinted, sending up tiny semi-transparent spheres on shining brownish stalks. As the changes approach maturity, the sporangia become jet-black, and only at last when the spores are ready for dispersal does the peridium a.s.sume its rich metallic purple tints. Colonies a meter in length, two or three decimeters in width, are sometimes seen!

New England, New York, Pennsylvania, Ohio, Indiana, Illinois, Iowa, South Dakota; Toronto. Common.

6. LAMPRODERMA ARCYRIONEMA _Rost._

PLATE V., Figs. 1, 1 _a_.