YU.000919

Made in United States of America
Reprinted from JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES
Volume 41, No. 9, September 15, 1951

BOTANY.—A *new species of Poa from Peru.* JOHN R. REEDER, Yale University.
(Communicated by Jason R. Swallen.)

In the spring of 1947 a small bundle of grasses was received from Dr. O. P. Pearson, now at the University of California. They were part of a collection of plants made by Dr. Pearson and his wife, in the region of Lake Titicaca in southern Peru. Among them were two collections of a species apparently undescribed. A description of this species is given below. Specimens are deposited in the Herbarium of Yale University, with duplicates in the United States National Herbarium and the Academy of Natural Sciences of Philadelphia. The type is at Yale.

*Poa pearsonii* sp. nov.

Perennis, dense caespitosa; innovationibus et basibus culmorum vaginis vetustioribus subcoriaceis fuscis vel fulvis dense vestitis; culmigerectis ad 50 cm altis gracilibus teretibus vel subcompressis scabris circiter 0.8 mm diametro, binodis, nodis in ⅔ inferiore culmi sitis; vaginis artis quam internodiis plerumque longioribus subcompressis scabris; ligula lanceolata acuminata, 10-15 mm longa; laminis anguste linearibus in-

volutis setaceis vel subjunceis, 0.8-1 mm diametro,
eis innovationum culmis subaequalibus, eis
summum culmi versus circiter 5-8 cm longis
scabris sectione transversa ovalibus 7-nerviis,
nervo mediano solo prominente; paniculis pyra-
midalibus subpatentibus, 10-12 cm longis, axi
scaberula, ramis capillaribus nutantibus, inferi-
ore 7-8 cm longo, ad ⅔ longitudinis nudis, apicem
versus spiculis instructis, ramis secundariis simi-
libus sed solo ⅓-½ longitudinis nudis, omnibus
4-6-spiculatis, pedicellis brevissimis clavatis scab-
ris; spiculis ellipticis confertifloris 5-6 mm.
longis praecipue 3-floris (raro 2-floris), flore basali
hermaphrodito, floribus superiorbus femineis cum
staminodiis minutis (raro floribus omnibus femi-
neis), rachillae internodiis brevissimis, flore se-
cundo a basali vix separato; glumis acutissimis
membranaceis laevibus, margine hyalinis; gluma
prima 4-4.5 mm longa, uninervia, gluma secunda
circiter 5 mm longa, quam flore contiguo paullo
breviore; lemmatibus omnino similibus ovato-
lanceolatis acutis, infimo 4.5 mm longo, superi-
oribus decrescentibus, dorso et latere scaberulis,

FIG. 1.—Ligules and spikelets, × 5: A, *Poa asveriflora*; B, *Poa pearsonii*. Note that in A the ligule is short, the lemmas are prominently nerved, and the florets are separated by rather long rachilla joints. In B, the ligule is very long, the lemmas are obscurely nerved, and the rachilla joint between the first and second florets is so short that these florets appear to be borne at about the same level.

YU.000919

VOL. 41, NO. 9

5-nerviis, nervis lateralibus obscuris quam lemmate brevioribus, callo glabro, carina basim versus puberula; palea quam lemmate paullo breviore, minute bidentata, carinis scabris; antheris in flore basali circiter 3 mm longis.

DEPARTMENT OF PUNO: Cerro Ichuasi, Cocchara, southwest of Llave, alt. about 4850 m, *O. P. & A. Pearson 91* (TYPE), November 22, 1946 (growing in gravelly soil at bottom of cliffs and alongside boulders; plants erect, in clumps, 25-50 cm tall).

The new species is apparently closely related to *Poa asperiflora* Hack., the type of which was collected in Bolivia on Titicaca Island at somewhat lower elevations. It differs from that species in having a much longer ligule, 2-noded culms and 3-flowered (rarely 2-flowered) spikelets in which the rachilla joints are very short, the second floret being scarcely raised above the basal one, the joint between the second and third floret somewhat longer. In *P. asperiflora* the ligule is about 4 mm long, the spikelets are pre-

dominantly 4-flowered (rarely 3-flowered), and the florets are separated by distinct rachilla joints, these ¼–⅜ the length of the florets. A further difference is seen in the florets, those of *P. pearsonii* tending to be somewhat larger and with obscurely nerved lemmas. The lemmas of *P. asperiflora* are very prominently nerved.

A second collection, *O. P. & A. Pearson 93*, from about the same location as the type but on a dry slope, appears to represent the new species. The spikelets are identical except that the florets are pistillate rather than perfect. The leaves are all distinctly shorter than the culm, and the culm seems to be 1-noded rather than 2-noded as in the type.

I wish to thank Jason R. Swallen, head curator, Department of Botany, United States National Museum, who kindly lent a type duplicate of *Poa asperiflora* Hack., and who also examined the Pearson specimens and confirmed my opinion that they represent an undescribed species.