1RboC>ora JOUKVAL OF THE NEW ENGLAND BOTANICAL CLUB Vol. 95 April 1993 No. 882 RHODORA, No. Vol. 85-96, 1993 95, 882, pp. THE HYBRID ORIGIN OF ELEOCHARIS MACOUNII Paul M. Catling and Stuart Hay G. ABSTRACT For nearly a century since description, Eleocharis macounii Femald has been its known with certainty only from the type station in Quebec. has been treated It synonym as a of either Eleocharis intermedia Schultes, E. obtusa (Willd.) Schuhes, & & E. ovata (Roth) R. or £. pahistris R. or as a hybrid. Various S. (L.) S., quantitative and qualitative morphological features suggest that a hybrid it is involving E. intermedia in series Palustriformes and E. obtusa in series Ovatae. Eleocharis x macounii best distinguished from sympatric species by rhizome is its mm many intemodes less than 2 long, presence of culms of varying lengths arising from a single tuft and pale greenish-brown achenes with prominent keels and a rough cellular surface. This natural hybrid is of particular interest since it is the first reported in the genus Eleocharis in North America, and involves different it species groups within the genus. Key Words: Eleocharis x macounii, Cyperaceae, hybrid, Quebec, North America INTRODUCTION known North America spikerushes, receiving increasing attention in is weed because of the potential use of several species in aquatic management and abatement systems pollution in irrigation in many The and of (e.g., Sutton, 1984). classification identification problem Femald Q Macoun North specimens by Wakefield, collected at J. bee. x macounii Marie- Victorin treated Eleocharis as a spe- (1^35) was known only from the Gatineau River. noting cies, that it species but suggested 85 BOTANICW; WISSOUW DEC 2 1993 ^tf\rvr^ lonAfsnl I Rhodora 86 [Vol. 95 problematic (Sm Manual Femald. Femald, Feraald 1908: 1950), North American Later macounii and he modification of E. obtusa (Willd.) Schultes, treated synonym monograph a of £. obtusa in his (1957) suggesting somewhere some slightly synonymy 980) placed E, macounii in with E. obtusa var. obtusa. 1 complex However. Hines (1975) in his monoaranh of the E. ovata mention either E. obtusa or E. ovata. Eleocharis synonymy same with E. intermedia, and treated in the it is names 1982). With synonym by Scoggan as a questionable of E. intermedia omitted by Boivin and not mentioned in the (1967), is Quebec eastern placed E. macounii in synonymy with E, ovata sensu lato (i.e., including E, obtusa). The only annotation on gh of Boivin (dated the type that at is material rhizomes On distinctive feature of the broken the isotype latter species, off. CAN intermedia Hay Femald. uncovered specimen also another from misidentified as £. intermedia, collected (Make summation cies, as part of the variation within one of four other taxa, or as The a hybrid. purpose of examine the present paper critically to is each of these and consider the hy- possibilities, particularly to pothesis that E, macounii of hybrid origin. is Hay— and Catling Eleocharis 87 1993] METHODS development was determined fruit mature from spikes from material, was stained using the phloxine and green technique fast (Owczarzak, 1952) to assess fertility. In order to determine whether E, macounii was intermediate were measured in quantitative characters, 10 characters (Table 1) in thirty specimens of each of E, intermedia, E, obtusa and E. These were over broad ovata. selected to represent variation a area of eastern Canada. For E. macounii two culms from the right hand group of and two from hand group on the the tufts left (mm) holotype were measured. Sheath length was measured from the base of the culm to the top of the sheath. Sheath width was Culm cm measured mouth. width was measured across the 1 Culm below from the inflorescence. height the distance the tip is of the spike to the base of the culm. Scales (also frequently referred to as bracts) measured were in cases taken from the middle of all the inflorescence. The length of the scarious margin of the scale was measured from margin back where was no the apical to it longer translucent. The length of the achene was measured from the base of the basal portion below the bristles to the base of the tubercle. and Tubercle width was used to separate E. ovata £". obtusa number and since more determined than stamen sep- easily it is Here with arates the species readily (Hines, 1975). plants a tu- mm bercle than wide are treated as E, ovata, while plants less .5 mm more wide with than are treated as E. obtusa. a tubercle .51 AND RESULTS DISCUSSION Femald Koch European macounii resembled the E. carniolica in that it He however, E, habit and inflorescence. correctly noted, that macounii has much broader tubercle (Figure IB) than E, car- a ofE. Furthermore the surface of the achene carniolica is niolica. not but rather obscurely wrinkled longitudinally clearly cellular, much more and the tubercle off. carniolica has a distinct neck. The European Eleocharis multicaulis (Sm.) Desv. similar to is much more E. macounii in some respects, but is a robust plant ' <., Rhodora 88 95 (Vol. m o — — c 1/^ 00 w^ iTi in m "^ r—- O<n <N ^ r^ t^ (N •^ ^^ tT w-^ v-^ »r> r-- — O O O — ' « « • • » « <N fN <7n i O ^ O O ^ o ^ n 8 O oo m 00 00 0^0 — <^ 00 oo (N so r- '^ '^ »ri — — • t # oo (N «N *N X O o oo \o oo 00 O ^ sO v^ "^ "^ so rn O O 00 i/^ (N oo' c OS OS v-^ so fN OS so O m O O O O O O r- O ^ ^ ^ i O O O m <N TT O so <N -^ ?N v^ Tf IN OO -^ v-i — — m O — — « » « • * » "^ <N 2 Tj- ' SO 00 SC SO so -^ r^l OS r- O O (N rs| ^ NO r- OO so oo Tj- O 00 u-^ 1- 00 r-i oo ^r\ OO \0 r^ r^ O O o — O O O O O » • ri ^_ ly^ f*^ w^ O ti o o ^ ^ VO vO so 00 o q q "^ 00 (N CM r^ rsi f*% — so 5 r^4 r^ OO O O O O 00 so — so rM c q so OS 00 vo r^ *^ r- -too i ON O — O ^ r^ w^ c O OOS Of-^ ^ oo <o f^ r^ r^ OS ("^ m o O O * « iTj rs| rsi 3 O o o o O O 00 — oo fS <N -^ ^ r- oo <N — o Q eg • « • 2 <N <N ri 00 O O r^ 00 "^ 30 "O O — f*^ Os OS O^ nO <^4 O O r^ E e E o s c C3 2*^ 3-2 ^ ^ II o "^ w ^ ^ Ce i ;i .5 s* g U £" 5 J » -^ ^ 6 -J B -S i e E o RS CO JJ ;j i* %» «> rs &i 1» 3 ^U, *5. "5. ^ < < 0i CO u) t/) c/} Hay— and Calling LVroc/ram 1993] 89 much and longer broader scales has ^^'^th spikes, also a slighily li longitudinally wrinkled aclicnr surface unlike munmmi. Thus E. E. macounii European not a introduction. is Boivin on suggested annotation his label that the type material of Eleocharis macounii referable to pa/ustn^ with rhi/oim-s is F.. broken This off. suggestion has to be rejected for several reasons: the cellular achene surface (Figure IB), the presence of culms of from var) ing lengths very short to vcr> long (Figure 2A), the fact many of culms from same on an arising the point abbreviated rhizome (Figure 2A), the elliptic scales (Figure 2C), the iclatlvely broad tubercle (Figure B) and the relatively pale grecnish-hrown 1 mature semu fruit are characters lacking in E. palusiris lato all (Figures ID, F, 2E, H), Including erythropoJa Stcudcl calm, (£. /:. and E. smallii Britton). The type material of £". macounii does not represent a freak, because the plants do not show any abnormal growth or infection. Only 10-30% of on of £. macounii have well the flowers spikes Many developed the remainder being aborted. Eleocharis fruit, and species including E. intermedia, E. ovata. E. obtusa invariably have 95-100% absence of the flower? ripening into achenes, in the of obvious fungus infection or insect attack. The high level of may be fruit abortion E. macounii suggests that a hybrid. in it The by hybrid concept supported pollen since further infertility is 40% only 10% of the pollen from one spike and of the pollen T from of macounii. took another both from the holotypc spike, 90% up more from L, the stain. In contrast than of pollen grains Even intermedia. E. and E. obtusa stained well. In the ovata. A*. maroumV pollen did the stain was often pale or confined that stain, pan to a small of the grain. on The and greenish surface of the achenes three-sided cellular, the holot>j'K^ plants ot Eleocharis macounii (Figure IBj is sug- although these characters gestive of E. intermedia (Figure lA), intermedia are less pronounced than In the latter species. If E. is one achene then the parent, as evidenced by the cellular surface, may expressed other parent be expected possess certain features to Among these characters in E. macounii. but not E. intermedia. in broad (Figure IB), a keeled that are be expected a tubercle to Is and and blunt, broad- long spike, lenticular achene, a relatively maqpn broad hyaline apically. iipped have sidles a relatively that ohtma (Figures There two general region: F. are possibilities in the ennhropoda IC, 2D) and 2G). Eleocharis E. ovata (Figures IE, 90 Rhodora 95 [Vol. 1^91 Hay— and 1993] Catling Eleocharis 91 known (previously widely as E. calva) and the E. smallii-palustris complex are eliminated as a source of putative parents because a hybrid of either of them with E. intermedia would be expected to have more pointed and broad-based and an achene with scales an and and elongate fleshy tubercle lacking prominently keeled edges, and rhizomes developed to a greater or lesser extent. Ele- ocharis macounii on the other hand has broadly rounded scales (Figure 2C), achenes with a relatively short tubercle and two or three prominently keeled edges (Figure and lacks an elongated 1 B), rhizome. Eleocharis obtusa and E, ovata, however, both possess many of the characters to be expected in the other parent, notably prominent on below the keels the achene, especially just the tu- Both and bercle. E. obtusa E. ovata possessed values for various quantitative characters, such as tubercle width (Figure IB) that were similar to E, macounii or intermediate with respect to £". intermedia. With regard to these two species, E. ovata has rela- tively short spikes and and smaller achenes (Table scales, 1), whereas and and achenes relatively longer spikes scales larger are predicted in the other parent E. macounii were to be inter- if mediate in these characters (Table Since intermediacy likely is 1). many more in features of hybrids, E. obtusa a likely parent. is It seems undesirable to recognize the varJejuna of the latter species The Labio and Hines, 1975). local rarity of £. ovata (Di (e.g., M, Make, Brunton, 4 1922, sub E, 1989; see also O. Sept. inter- media, can) and the that has not been found at Wakefield, fact it common, more where E. obtusa also suggests that the latter is is likely to be the other parent. Eleocharis x macounii appears be the hybrid reported to first North America, and should in the genus Eleocharis in at least it more widespread raise the question of whether hybridization is some and with in the genus than currently recognized, associated of taxonomic the difficulties. have been reported from Japan Natural hybrids Eleocharis in Koyama, and hybrids in Eleocharis subseries Palus- 1961), (e.g., documented Europe have been well (Strandhede, 1965) tres in A of Eleocharis intermedia {Catling 7/09/87, Figure Representative fruits 1. D C DAo). B X macounii {Macoun 7552, gh). E. obtusa {Cody 6579, dao). E. E. F pahistris 11765, dao). E E, ovata {Dure 24360. dao). E. erythropoda {Gillet Drawings by Marcel Jomphe. (Rolland-Germain 10284, dao). ^ Rhodora 92 [Vol. 95 A 1cm 1 B Imm I I C-H 1mm B l^^^j^-^U^ i'i^l A-C Figure x {Ma Eleocharis macounii 2. D-H D species. £. oZ^m^fl {Cody 6759, dao). E eryihropoda {Rolland-Germain 10284, £". H F G DAO). E. intermedia {Catling 1/mmi, dao). E. ovata {Dore 24360, dao). Marcel E. smallii {sub E. palustris var. majon 11765, dao). Drawings by Gillet Jomphe. \ Hay— and Catling 1993] Eleocharis 93 with cytological studies. Eleocharis mamillata subsp. mamillata X E. palustris subsp. palustris has greatly reduced > fertility. It is to be expected that a hybrid between quite different species in different series (as treated by Svenson, 957), like E. x macounii, 1 would also have reduced The chromosome number of fertility. 2n= E, obtusa whereas E. intermedia has been is 1 0, reported with 2n=22 (Schuyler, 1977), so that if living plants of £. xmacounii are discovered, it should be possible to support the putative par- entage with both chromosome number and meiotic anomalies. Unfortunately repeated attempts by the authors and other bota- x nists to locate living material of £". macounii at the type station and elsewhere have been unsuccessful. The following key and description, based on the type material and one other collection, will facilitate the identification of E. x macounii. KEY TO THE ELEOCHARIS OF SPECIES AND SOUTHERN ONTARIO QUEBEC WITH AND DIFTERENTIATED TUBERCLES, FIRM SHEATHS ACHENES LACKING LONGITUDINAL RIDGES mm Rhizome intemodes more than 2 long, tufts with most 1. culms of similar height 2 Achenes with a roughened cellular or reticulate surface, 2. 3-sided perennials of Palustriformes subseries Trunca- series . . and tae including E. compressa, E, eUiptica E. nitida Achenes smooth and most only ob- 2. essentially shiny, at scurely cellular or reticulate, 2-sided perennials of series Palustriformes subseries Palustris , . and including E. erythropoda E. smallii mm Rhizome internodes than 2 long, tufts with culms of less 1 . many and ages heights 3 different Achenes with roughened cellular or reticulate surface 4 a 3. mm becoming Longer 5-7 achenes dark spikelets long; 4. prominent green, without keels, subterete to equilat- 0.18-0.22 eral triangular in cross section; tubercles mm wide E, intermedia mm Longer 8-1 spikelets 4. 1 very J Rhodora 95 94 IVoi. more tuber- or lenticular in cross section; bercle, less mm x macounii wide E. (0.2)0.3-0.5 cles smooth Achenes with a surface 5 3. mm wide E. ovata Tubercle than 0.5 less 5. mm more wide E. obtusa Tubercle or 0.51 5. x macounii Femald intermedia Schultes Eleocharis {pro (E. sp,) Amer. Acad. 497, X E. obtusa (Willd.) Schultes), Proc. 34: Figure 26a. 1899. Macoun (holotype- Type: Quebec, North Wakefield, Sept. 893, 75.5.2 3 /. 1 1 isotype— gh! can!). mm culms Annual rhizome intemodes than 2 long, herb; less down- bending red the base, green above, erect to divergent or at mm 20-230 and varying lengths ward, numerous, long of greatly mm cm within a 0.3-0.8 wide below the inflorescence; tuft, 1 mm mm uppermost sheaths 5-35 long, 0.3-0.9 wide at the acute 3-11 5-52-flowered, apex. Spikelets lanceolate, acute, densely mm mm mid- long, 1.5-3 wide; scales reddish-brown with green mm rib, ovate, obtuse, those in the middle of the spikelet 1.8-2.5 mm mm wide long, 1-1.3 wide, with a scarious margin 0.1-0.2 mm 0.2- at the apex. Stamens filaments 0.9-2 long, anthers 3, mm by 0.4 long, not reaching to the top of and concealed the subtending mostly oc- scale, pollen largely Styles trifid, infertile. mm beyond casionally bifid, the branches 0.5-0.9 long, extending those the tip of the subtending Achenes mostly aborted, scale. 0.9- maturing pale greenish-brown when mature, obovoid, fully mm mm mostly long with 1.1 (excluding tubercle), 0.6-0.8 wide, 3 (sometimes keels becoming very prominent toward the apex, 2) de- the surface rough-cellular, with or rectangular circular i.e., mm pressions with elevated 0.3-0.4 high, walls; tubercle deltoid mm 0.2-0.5 wide; brown, barbed, bristles (4)5-6(7), retrosely mm mostly much and .2-2. long, exceeding the achene tubercle. 1 1 Malte Additional material examined: Quebec: Cascades, 7-8-1913, M. O. s.n. (can). both from and Cascades, Distribution: Collected only Wakefield localities along the Gatineau River of Quebec. and Comments: x rhizomes Eleocharis macounii elongate lacks and E. has the tufted or caespitose growth habit of E. obtusa many lengths intermedia, as well as flowering/fruiting culms of more as in these species. This latter feature, as well as the or less