THE SILVA OF COLORADO

III. WOODY PLANTS OF BOULDER COUNTY

BY FRANCIS RAMALEY

Introduction. This paper is intended as a preliminary report on the trees, shrubs and vines of Boulder County. It is hoped that the general discussion which follows, as well as the annotated list, may be useful to students, botanists or others interested in woody plants. Since the character of the flora is about the same all along the eastern foothill region in Colorado north of the Palmer Lake divide, most of the facts stated here will be of more general application than if Boulder County were a region apart.

Sources of material.—Collections for the University of Colorado herbarium were first made by Mr. J. I. McFarland in 1881. In 1895 and 1896 Mr. F. Y. Moseley, at that time an assistant in the department of biology, collected some specimens at Long's Peak and other alpine and sub-alpine stations. In the summer of 1900 and from time to time since then the author has made collections in various parts of the county. Most of the Boulder County plants now in the herbarium are of these collections. During 1906 and 1907 the writer was assisted by Mr. W. W. Robbins, a graduate of the University. The larger part of the author's collections have been identified by Professor Aven Nelson of the University of Wyoming without whose accurate determinations the publication of this paper would be impossible at the present time. The valuable work of Dr. P. A. Rydberg has been consulted constantly and specimens cited by him in Boulder County are noted in the following list, credit being given in each case. Dr. Robert T. Young, now of the University of North Dakota, but formerly a resident of Boulder, made collections in the county but I have not seen his plants.3

Mr. McFarland was a member of the first graduating class of the University.

Flora of Colorado, Bull. 100, Agr. Exp. Sta., Colo. Agr. Coll. 1906.

Dr. Young has prepared a valuable paper on the "Forest Formations of Boulder County" just published in Botanical Gazette, Vol. XLIX, pp. 321-352.

1907.

of woody plants

Trees

50 genera. peraceae, Salicaceae, -sceae, Caprifoliaceae. rody plants: Pinaceae, ... Caprifoliaceae. Other Interest to point out that abundant at Morrison, to the north.

unty. This list is merely necessary. Species should Sniperus, Sabina, Salix, Ribes, Robinia, Acer, Ceanothus S and Symphoricarpos. Sumber: Pinus flexilis, Pinus gelmanni, Pseudotsuga mucro's or used for fuel, in addition to of the species of Populus and for shade or ornament: nearly all the poplars or cottonwoods, but Populus acuminata; some of the which are seldom planted but which ment: Betula andrewsii, Betula fonti

spp., Acer glabrum. Many of amental. Some of the following have Segre but more might be used: Berberis Ribes longiflorum, Dasiphora frutiaster monogynus, Opulaster ramaleyi, res fors, some of the species of Amelanchier, reiutinus, Lepargyraea canadensis, Cornus maefolium, Distegia involucrata, Sambucus

e County.—The accompanying map gives the **ntains as well as the towns in the county. of foothills" noted on the map there is plains

Families and genera represented.—The 112 species of woody plants listed for the county are distributed in 29 families and 50 genera. Trees occur only in the following families: Pinaceae, Juniperaceae, Salicaceae, Betulaceae, Ulmaceae, Pomaceae, Drupaceae, Aceraceae, Caprifoliaceae. Families represented by 7 or more species of woody plants: Pinaceae, Salicaceae, Grossulariaceae, Rosaceae, Pomaceae, Caprifoliaceae. Other families have only a few species each. It is of interest to point out that no oaks occur in the county although they are abundant at Morrison, to the south, and some occur in North Park, to the north.

Other woody plants probably in the county.-This list is merely preliminary. More complete collections are necessary. Species should be looked for in the following genera: Juniperus, Sabina, Salix, Ribes, Rosa, Amelanchier, Prunus, Amorpha, Robinia, Acer, Ceanothus Lepargyraea, Phyllodoce, Cornus, Sambucus and Symphoricarpos.

Economic plants.-Trees used for lumber: Pinus flexilis, Pinus scopulorum, Pinus murrayana, Picea engelmanni, Pseudotsuga mucronata. Trees furnishing posts and rails or used for fuel, in addition to the above list: Sabina scopulorum, all of the species of Populus and some of the willows. Trees planted for shade or ornament: nearly all the Pinaceae and Juniperaceae; all the poplars or cottonwoods, but more often Populus sargentii and Populus acuminata; some of the willows, also box elder. Trees which are seldom planted but which might prove valuable for ornament: Betula andrewsii, Betula fontinalis, Celtis reticulata, Crataegus spp., Acer glabrum. Many of the native shrubs would be ornamental. Some of the following have been introduced to a slight degree but more might be used: Berberis aquifolium, Edwinia americana, Ribes longiflorum, Dasiphora fruticosa, Holodiscus dumosus, Opulaster monogynus, Opulaster ramaleyi, Rubus deliciosus, Rubus parviflorus, some of the species of Amelanchier, Sorbus scopulina, Ceanothus velutinus, Lepargyraea canadensis, Cornus stolonifera, Apocynum androsemaefolium, Distegia involucrata, Sambucus microbotrys.

Geography of Boulder County.-The accompanying map gives the important streams and mountains as well as the towns in the county. East of the "front ridge of foothills" noted on the map there is plains