UNIVERSITY OF

ILLINOIS LIBRARY

AT URBANA CHAMPAIGN

%^ ^ ^BIOLOGY

JUL11198*

8 FIELDIANA

7 Botany

Published by Field Museum of Natural History

Volume 38, No. 2 April 30, 1976

New Species of

Digitaria, Pennisetum,andPoa (Gramineae)

from Costa Rica1

RICHARD W. POHL

DEPT. OF BOTANY AND PLANT PATHOLOGY

IOWA STATE UNIVERSITY

AMES, IOWA

Descriptions of four endemic grasses from Costa Rica, Digitaria

costaricensis, Pennisetum tempisquense , Poa talamancae, and Poa

chirripoensis, are given. Chromosome number of D. costaricensis is

n = 27 and that of P. tempisquense n = 36.

Fractions stated after shapes of structures indicate length/width

proportions.

Digitaria costaricensis Pohl, sp. nov.

Sect. Aequiglumis Henrard pertinens, D. aequiglumi (Hack, et Arech.) Parodi

similis, sed ab eo foliis dense papilloso-pilosis, laminis latioribus, racemis longi-

oribus, gluma prima truncata, nervis glumae secundae 5-7 et lemmatis sterilis 7-9,

antherisque purpureis 0.9-1.5 mm longis recedens.

Probably perennial; plants with long decumbent rooting culm bases, up to 80 cm.

long, sometimes becoming buried and appearing rhizomatous; culms 1-3 mm. thick,

hollow, thick-walled, glabrous, branching abundantly from lower and middle nodes;

prophylla up to 2 cm. long, papillose-pilose; sheaths mostly longer than the inter-

nodes, densely retrorsely papillose-pilose, the hairs silky, up to 3.5 mm. long; ligule

a thin erose membrane, 1.5-2.5 mm. long, decurrent on the sheath margins; blades

soft, flat, 8-15 cm. long, 3.5-7.0 mm. wide, softly velvety. Peduncle glabrous, ex-

serted up to 15 cm.; inflorescences terminal on erect leafy branches, 7-14 cm. long,

narrow and erect, the 4-7 racemes borne on a short rachis up to 2-3 cm. long; several

'Journal Paper No. J-8146 of the Iowa Agriculture and Home Economics Experi-

ment Station, Ames, Iowa, Project No. 1833. Facilities of the Iowa State University

Herbarium, supported by the Science and Humanities Research Institute, were

used in the preparation of this paper. The work was aided by National Science Foun-

ation Grants GB-7307 and GB-32085. The author thanks Mr. Rupert Barneby of the

New York Botanical Garden for revising the Latin diagnoses.

Library of Congress Catalog Number: 75-46385

US ISSN 0015-0746 The ybrary of th«

Publication 1228

NQV091976

university ot mmo*

"

6 FIELDIANA: BOTANY, VOLUME 38

short racemes of 1-several spikelets borne at the base of the longer racemes. Spike-

lets paired, rather remote on the slender triquetrous rachis, which is strongly scab-

rous on the angles; subsessile spikelet reaching about to the base of the spikelet

next above it; spikelets of the pair equal, 3.5-4.0 mm. long; shorter pedicel 0.5-0.7

mm. long, the longer one 2.0-3.0 mm.; spikelets acute, narrowly ovate 3.5-4.0/1; first

glume a thin, evanescent, nerveless, truncate, cuff-like scale, ca. 0.3 mm. long;

second glume and sterile lemma equal, slightly longer than the fertile floret, both

with short silky white hairs on the margins and in the outer internerves, somewhat

silky on the back above the base and with scattered hairs on the remainder of the

back; second glume slightly narrower than the sterile lemma, but covering the fer-

tile floret completely, 5-7-nerved; sterile lemma similar, 7-9-nerved, the nerves equi-

distant; fertile floret 3.0-3.2 mm. long, the lemma narrowly ovate, acute, stria te,

grayish, faintly 3-nerved, the palea equal; stamens 3, the anthers purple, 0.9-1.5

mm. long; stigmas purple. Mature fruit not seen.

HOLOTYPE: Costa Rica: Prov. Cartago. 25 km. S of El Tejar

along the Carretera Interamericana; elev. 1,780 m. In roadside

ditch. Plants very villous, inflorescence branches erect. Chromo-

some number n = 27. Oct. 8, 1968. Pohl SaDavidse 11215. Holotype

in ISC; isotypes in F, US, UC, CR, K, L.

Other collections: Costa Rica: Prov. Cartago: Rio Macho Reser-

voir, 1,700 m. elevation, Oct. 3, 1968, Pohl &Davidse 11190; 2 km.

W. of Paraiso, along drainage ditch, April 21, 1969, n = 27, Pohl &

Davidse 11789.

This species occurs at middle elevations in the region east and

south of Cartago. It is a member of the section Aequiglumae Hen-

rard, Monog. Digitaria 641. This is a group of about 16 species

native to the American tropics and subtropics, the members having

equal paired spikelets with the first glume small or absent. The

second glume and sterile lemma are subequal and usually exceed the

fertile floret. Among this group, Digitaria costaricensis seems most

similar to D. aequiglumis (Hack, et Arech.) Parodi, from which it

differs in the following characteristics: heavily pubescent foliage,

wider leaf blades, longer racemes, presence of a cuff-like first glume,

more numerous nerves of the second glume and sterile lemma,

longer anthers.

Pennisetum tempisquense Pohl, sp. nov.

A P. complanato (Nees) Hemsl. habitu caespitoso non rhizomato, setis minus

numerosis albidis, spicularum acuminatarum flosculo infimo sterili, stylisque 2 inter

se separatis differt. A P. nervoso (Nees) Trin. culmis solidis, inflorescentiis minori-

bus, setis minus numerosis, spicularum breviorum gluma prima breviori necnon

chromosomatum numero n = 36 recidit. P. frutescenti (2n = 63) similis sed ab eo

habitu caespitoso, culmis solidis, statura minora et chromosomatum numero dis-

tans.

FlG. 1. Digitaria costaricensis. Scale lines = 1 mm.

8 FIELDIANA: BOTANY, VOLUME 38

Caespitose perennial; plants 39-100 cm. tall; culms erect, unbranched, densely

clustered, glabrous, glaucous, rather thin walled, the interior filled with paren-

chyma; nodes glabrous, constricted, dark; leaves ca. 7 per culm; sheaths mostly

shorter than the internodes, compressed and keeled, glabrous and glaucous, the

margin thin and membranaceous; ligule a short membrane, densely long-ciliate, 1.0-

1.8 mm. long; leaf blades flat or folded, keeled near the base, firm, scabrous-mar-

gined, the base narrower than the summit of the sheath, glabrous and glaucous, 4.5-

7.5 mm. wide, 8-22 cm. long, the uppermost shorter. Peduncle exserted; inflores-

cence a stiff and erect solitary terminal spike of fascicles, whitish, 7-10 cm. long, 2.0-

2.5 cm. thick, including the bristles; rachis ca. 1 mm. thick, longitudinally striate,

densely short-hispid; fascicles crowded, horizontally spreading, mostly 10-14 mm.

long, borne on minute projections of the rachis; bristles ca. 20 per fascicle, whitish,

of varying lengths, the outermost 3-4 mm. long, the majority 8-10 mm. long, the

innermost one longer and thicker, 12-17 mm. long, all straight, upwardly scabrous,

attached to a short, rounded common stipe ca. 0.2-0.3 mm. long. Spikelet one per

fascicle and sessile within it, narrowly ovate, acuminate, 5-6 mm. long; first glume

ovate, 1.0-1.5 mm. long, acute to rounded, scarcely nerved, membranaceous; second

glume, lower lemma, and upper lemma subequal, acuminate or awn-tipped; second

glume 5.0-5.5 mm. long, striate, 7-nerved; lower lemma 5.7-5.9 mm. long, 5-nerved,

without a palea or flower; upper lemma 5.2-5.7 mm. long, faintly 5-nerved, the palea

about equal, 2-nerved, acuminate; anthers purple, 1.2-1.5 mm. long; ovary with 2

separate styles; stigmas purple; caryopsis oblong, tan, 2.1-2.2 mm. long. Chromo-

some number n = 36, determined from the type, Pohl 8iDavid.se 11725. (Published

originally as P. nervosum in Pohl & Davidse, 1971).

HOLOTYPE: Costa Rica: Prov. Guanacaste: 8 km. N of Haci-

enda Palo Verde, 14 km. WSW of Bagaces. Elev. 10 m. Black gumbo

clay flats. Pohl & Davidse 11725. Feb. 20, 1969. Holotype in ISC,

isotypes in US, K, F, UC, CR. Progeny grown from seed of the holo-

type in the Iowa State University greenhouse are in ISC as Pohl

12987.

This species differs from the widespread P. complanatum (Nees)

Hemsl. in being caespitose rather than rhizomatous, in the fewer,

more slender whitish bristles, the acuminate spikelets with sterile

lower floret, and the separate styles. It differs from the South

American P. nervosum in its smaller size, solid culms, smaller inflo-

rescences, fewer bristles, shorter spikelets with short first glume,

and chromosome number (n = 36, that of P. nervosum being n =

18). It appears similar to P. frutescens Leeke of southern South

America, from which it differs in its solid culms, longer bristles,

smaller size, lack of rhizomes, and different chromosome number.

Pennisetum frutescens has 2n = 63 (Nunez, 1952). The specificname

is derived from the Rio Tempisque, near the type locality.

Poa talamancae Pohl, sp. nov.

P. orizabensi affinis sed ab ea foliis basalibus planis crebris, nodis caulinis 3, ligu-

lis longioribus, spiculis majoribus, necnon lemmatibus longioribus abhorrens.

FlG. 2. Pennisetum tempisquense. Scale line for inflorescence = 1 cm. , for spikelets

and parts = 1 mm.

10 FIELDIANA: BOTANY, VOLUME 38

Gramen perenne caespitosum, basi dense foliatum, foliis planis laxis; panicula parva

tenella, ramis binatis vel solitariis flexuosis; spiculae 2- 3-florae; lemmata basi spar-

sim comata.

Plants perennial, caespitose in dense tufts with abundant basal foliage; sheaths of

basal leaves keeled; blades flat, olivaceous, 3-14 cm. long, 2-4 mm. wide, their sur-

faces minutely scaberulous, the margins scabrous, tip conspicuously cucullate;

basal foliage often floccose with fungus hyphae; culms erect or somewhat decum-

bent at the base, slender, 20-60 cm. tall; internodes 3, ca. 1 mm. thick, hollow, glab-

rous, slightly scabrid, with a light-colored band just below the prominent, purple

nodes; culm leaves usually 3; sheaths much shorter than the internodes, glabrous,

slightly keeled and scabrid on the keel; ligule a thin membrane, up to 2 mm. long;

blades of culm leaves flat, 2-6 (-14) cm. long, 2-4 mm. wide, the uppermost usually

short. Peduncle exserted up to 11 cm.; inflorescence a solitary terminal panicle, 8-11

cm. long, up to 6 cm. wide, very open, the solitary or paired slender flexuous

branches up to 3 cm. long; spikelets few, appressed along the outer halves of the

branches. Spikelets 4.5-5.6 mm. long, laterally compressed, usually purple; glumes

shorter than the florets, the first ovate as folded, 1-nerved, 1.8-2.9 mm. long; second

glume oblong to obovate, 3-nerved, 2.3-3.4 mm. long, both glumes scabrous on the

keel; florets 2-3, the rachilla prolonged beyond the last as a slender bristle one-third

to one-half as long as the floret, sometimes bearing a minute rudiment at its tip;

lemmas oblong-obovate in side view, 5-nerved, 3.1-4.1 mm. long; lower third to half

of the keel silky -ciliate, as also the basal portion of the marginal nerves; upper part

of the keel and surface of the lemma scabrid; at least the lowermost lemma bearing a

scant cottony web on the callus; palea about equal to the lemma, scabrous on the

keels; anthers 3, yellow, 1.1-1.3 mm. long; caryopsis brown, narrowly ovoid, 2 mm.

long.

HOLOTYPE: Costa Rica: Prov. San Jose: Asuncion Summit of

Cerro de la Muerte. Elev. 3,335 m., open windswept paramo. July

22, 1966. Mori & Anderson 214. ISC, WIS.

Other specimens: Costa Rica: Prov. Cartago: Paramo, elev. ca.

3,500 m., Cerro de la Muerte. Feb. 26, 1965. Godfrey 66754. US,

FSU; Costa Rica, without locality or date: Jorge Leon 2714. US.

Poa talamancae is not closely related to any other species of Poa

found in Costa Rica. It could probably be assigned to the informal

group "Palustres" of Hitchcock. It appears most similar to P. ori-

zabensis Hitchc., Contrib. U. S. Nat. Herb. 17: 374. 1913, a Mexican

species, from which it differs in the abundant soft, flat, basal leaf

blades, three stem nodes, longer ligules, and larger spikelets with

longer lemmas. The specific name is derived from the Talamanca

Range.

Poa chirripoensis Pohl, sp. nov.

Gramen perenne dense caespitosum, foliis basalibus elongatis erectis rigidis con-

duplicatis apiculatis; panicula parva; spiculae 1- 2-florae; lemmata pilis rigidis

brevissimus apice rotundatis lineolatim scabra basique sparsissime comata.

Perennial; densely caespitose; culms erect, unbranched, 37-50 cm. tall, hollow,

glabrous, elliptical in cross-section; nodes not prominent, dark; basal foliage abun-

FIG. 3. Poa talamancae. Scale lines = 1 mm.

11

FlG. 4. Poa chirripoensis. Scale line = 1 mm.

12

POHL: NEW GRASSES OF COSTA RICA 13

dant, the blades stiff, erect, up to 20 cm. long, reaching about to midculm; sheaths

keeled, slightly scabrid, those of the 2-3 short culm leaves shorter than the inter-

nodes; ligule a thin membrane, 2.0-4.5 mm. long, tapering abruptly to a point; leaf

blades 2-3 mm. wide, stiff, permanently folded, erect, tapering abruptly to a sharp

rigid cusp, the surfaces minutely roughened. Peduncle smooth, exserted 7-25 cm.;

inflorescence a solitary terminal panicle, open, pyramidal, 6-8 cm. long, 3-5 cm. wide;

branches paired, spreading, flexuous, bearing a few peg-like hairs like those of the

lemmas; pedicels thick, scabrous in lines with similar hairs; spikelets clustered

toward the outer ends of the branches. Spikelets 3.7-4.4 mm. long, 1- 2-flowered, the

glumes keeled, 3.5-4.0 mm. long, nearly as long as the florets; first glume triangular

5/1 as folded, the second slightly wider, both 3-nerved, tapering to acuminate tips,

scabrous on the keels and nerves; lemmas ovate, 3.5-3.9 mm. long, 4/1-5/1 as folded,

blunt tipped, densely scabrous in lines with thick, stiff, round-tipped hairs 0.05-0.10

mm. long; callus usually with a few short cobwebby hairs; palea nearly as long as

the lemma, scabrous on the keels with hairs similar to those of the lemmas.

Known only from the type, collected on the summit of Chirripo

Grande.

HOLOTYPE: Costa Rica: Prov. San Jose: Among rocks on top of

Chirripo at 3,820 m. Forming tufts. Open paramo formation with

stands of Chusquea bamboo 1-2.5 m. tall. 9°30'N, 83°31'W. Burger &

Liesner 7448. Jan. 19-22, 1970. Holotype in F; isotypes in ISC, US,

CR.

This species is easily distinguished from others in Central Amer-

ica by its dense clusters of erect basal leaves, and by the unique

rigid spicule-like hairs of the lemmas. It is not closely related to any

other North American species.

REFERENCES

HENRARD, J. TH.

1950. Monograph of the genus Digitaria. Univ. Pers Leiden.

NUNEZ, O.

1952. Investigaciones cariosistematicas en las Gramineas Argentinas de la tribus

"Paniceae." Rev. Fac. Agron. La Plata (Eva Peron), 28, pp. 229-256.

POHL, R. W. and G. DAVIDSE.

1971. Chromosome numbers of Costa Rican grasses. Brittonia, 23, pp. 293-294.

UNIVERSITY OF ILLINOIS-URBANA