Pollen morphology of Lagotis (Scrophulariaceae)

Pollen morphology of Lagotis (Scrophulariaceae)

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Charles L. Argue

Abstract: The pollen grains of 18 species of Lagotis have been examined using light microscopy and scanning electron microscopy of whole and fractured pollen. The grains are characterized by tricolporate apertures with smooth to sparsely granular ectocolpus membranes; lolongate endoapertures with unthickened margins included within the ectocolpi; relatively large exinous processes over the endoaperture; and columellate, semitectate, reticulate to microreticulate exines with o r without supramurial processes. Lumina are reduced in size toward the colpus, but the transition is gradual, and a sharply bounded, differentially sculptured colpus border is absent. Lagotis pollen is distinct from that of the Selagineae and Globltlaria and indistinct from that of some Veroniceae; however, the characters shared with the latter are of wide occurrence in the Scrophulariaceae. Pollen morphology supports the distinction between L. brachystachya and L. srolon$era. It is consistent with the postulated close relationship between L. micrantha and L. integra, and provides no evidence to support the reestablishment of L. cashmeriana, L. minor, L. pallasii, o r L. k~mawurensisas species distinct from L. glauca. Key words: pollen morphology, Lagotis, Globularia, Selagineae, Veroniceae.

ResumC : L'auteur a examine les grains de pollen de 18 espkces de Lagotis, B I'aide de la microscopie photonique et Clectronique par balayage, en utilisant des pollens entiers ou fractures. Les grains sont caractCrisCs par des ouvertures tricolpories avec des membranes ectocolpaires lisses ou faiblement granulaires; des endopores lolongCs avec des bordures non-Cpaissies, inclus dans les ectocolpes; des appendices de I'exine relativement importants au dessus de l'ouverture; des exines columellCes, semitectkes, de rCticulCes ?I microrkticulCes, avec ou sans appendices supramuriales. Les lumens sont de dimensions rCduites vers le colpus, mais la transition est graduelle et il n'y a pas de bordure du colpus nettement dklimitke avec sculptures diffkrentielles. Le pollen des Lagotis est distinct de celui des SClaginelles et des Globularia et indistinct de celui de certaines Veroniceae; cependant, les caractkres partagCs avec ces dernikresse retrouvent frCquemment chez les Scrophulariaceae. La morphologie des pollens confirme la distinction entre les L. brachystachyn et L. stolon$era. Ceci est conforme avec les prCsumCes Ctroites relations entre les L. micrantha et L. integra, et ne fournit aucune preuve pour supporter le retour des L. cashmeriana, L. minor, L. pallasii ou L. kunawurensis comme des espkces distinctes du L. glauca. Mots clfs : morphologie pollinique, Lagotis, Glob~llaria,Selagineae, Veroniceae. [Traduit par la rkdaction]

Introduction Lagotis Gaertner is a small genus of herbaceous plants distributed from eastern Europe and Asia Minor to the Himalayas and from western China to Alaska and the Yukon (Pennell l933; Li 1954; Willis 1973; Mabberle~1987). Its relationships have been the subject of much discussion. Many early workers, for example, Endlicher ( 1836- 1840), Bailion 888), and Wenstein 89 assigned it to tribe Veroniceae (Digitaleae) of the Scrophulariaceae, and this treatmerit was Pennell Thieret (1955, 1967), and Engler (1964). Van Tieghem (1891) and Thieret (1955) also included Globularia in this tribe and placed 7

Received August 5 , 1994.

C.L. Argue. Department of Plant Biology, 220 Biological Sciences Center, 1445 Gortner Avenue, University of Minnesota, St. Paul, MN 55108, U.S.A. Can. J . Bot. 73: 701 -709 (1995). Printed in Canada / Imprime au Canada

it close to Lanotis. - Yamazaki (1957)., . however, excluded both Globularia and Lagotis from the Veroniceae, a treatment accepted by Hong (1984). Like Wettstein (1895), Yamazaki put Globularia in the Globulariaceae and, following a number of earlier workers (e,g., Bentham 1846; Choisy 1848; Bentham and Hooker 1876; Rolfe 1883, 1901; Van Tieghem 189l), assigned Lagotis to the Selagineae (Selaginaceae). Lagoris has sometimes been considered a ..taxonomic link.. between the Scrophulariaceae - Selagineae and (Jobularia (e.g., Willis 1973). Finally, both Lagotis and Globularia have been included by some authors in the Selagineae (e.g.,

Hooker 1885). The principal character usually cited in support of a relationship among Lagotis, Globularia, and (or) the Selagineae is the reduction of ovule number in all three taxa to one per loculus, with the production of fruits containing only one or two large seeds. However, low seed number in conjunction with large seed size is common in other taxa of the Scrophu-

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Table 1. Summary o f pollen morphological data for Lagotis.

Taxon

L. L. L. L. L. L. L. L. L. L. L, L. L. L. L. L. L. L.

alutacea brachystachya brevituba crassifolia decumbens glauca globosa integra irztegrifolia korolkowi lancilimba rnicrantha rarnalana rockii stolonifera takedana wardii yutltlanerzsis

Polar axis (PI

24 32 -36 31 -32 3 1 - 35 29-33 29-38 30-37 27 29 -33 32-40 29-32 25 31 27 34-42 31 -36 26 32 -40

Equatorial axis (E)

P/E

PID

Endoaperture Endoaperture height width (H) (w)

H/W

Mean Exine maximum thickness lumina

Free Supramurial sculpturing ornamentation" elements"

Tectuma r , m, (ir), (im) m , r, (im), ( i d r, (id r, ( i d r , ir r, r, r, r,

m , ( i d , (im), (id (id ir

(4

m , (r), (im), ( i d r, ir r, ir r r, (id m , im, st

m, (r), (im), ( i d r7 ir, (m) r, m , im, ir, (st)

NOTE: Measurements are of the range of specimen means and are in micrometres. PID, polar intercolpal distance; mean maximum lumina, mean maximum diameter of lumina on mesocolpium. "im, irregularly microreticulate; ir, irregularly reticulate; m, microreticulate; r, reticulate; ru, rugulate; st, striato(micro)reticulate. Descriptors in parentheses apply sometimes. present; -, absent; v, variable.

"+,


lariaceae and is evident elsewhere in the Veroniceae in Synthyris, subgenus Plagiocarpus, and sometimes in Veronica (Pennell 1933). According to Willis (1973) and Mabberley (1987), Lagotis includes 20 species. Index Kewensis lists about 28, 18 of which are included in the present study. A number of taxa recognized as distinct species by some authors and varieties or subspecies of L. glauca by others are here grouped with L. glauca pending revision of this complex (see Discussion). Preliminary studies (Argue 1993) demonstrated that pollen grains in some species of Lagotis differ significantly from those in the Selagineae and Globularia. The acquisition of additional material now permits a more complete comparison of the pollen of these taxa.

Materials and methods All pollen grains were taken from herbarium specimens, and standard abbreviations of herbaria (Holmgren et al. 1990) are used to indicate the location of vouchers. Pollen was, in most cases, removed from collections identified by specialists such as A.F. Batalin, H.F. Handel-Mazzetti, E. HultCn, H. Li, F.W. Pennell, B. Schischkim, T. Shimizu, W.W. Smith, A. Vvedensky, and T. Yamazaki. Authors and specimens examined are included in the Appendix. Acetolyzed and unacetolyzed pollen grains from 18 species and 48 specimens were investigated by light microscopy (LM) and scanning electron microscopy (SEM) of whole and fractured grains. Methods of pollen preparation, examination, and measurement have been described previously (Argue 1984). In most cases, 10-20 regularly shaped and fully expanded grains were measured per specimen. Pollen diameter, outlines in polar and lateral view, and endoaperture dimensions and shape were determined by LM of unacetolyzed grains. Distances between the polar ends of the colpi are given instead of polar area indexes, as they can be measured accurately on both acetolyzed and unacetolyzed pollen and are not subject to variation resulting from differences in equatorial diameter. Lumina dimensions were derived from LM and SEM measurements. SEM and all illustrations and other descriptions were based on acetolyzed pollen. Measurements included in the text represent a range of species means. The range of specimen means is given in Table 1. Terminology follows Erdtman (1952), Faegri and Iversen (1964), Praglowski and Punt (1973), and Walker and Doyle (1975). For endoapertures, height is the meridional dimension measured at the center of the ectocolpus, and width is the equatorial dimension. Granules are distally rounded sculpturing elements with diameters more or less equal to or greater than their height.

Results Selected LM and SEM data are summarized in Table 1. The pollen grains of Lagotis are solitary, radially symmetrical, isopolar, and trizonocolporate (e.g., Figs. 1, 3, 6, 11, 16, 36, 39, 43, 44, 51), although tetrazonocolporate apertures and various aberrant colpus arrangements occur in a small proportion of grains in some taxa (Fig. 12). The mean polaraxis length ranges from about 24 to 38 pm, and the mean ratio of polar-axis length to equatorial diameter (P/E ratio)

from 0.92 (oblate spheroidal) to 1.20 (subprolate). The outline in lateral view is elliptic to circular; in polar view circular, sometimes with more or less sunken colpi. Some grains in a few collections are slightly angular with more or less convex sides and apertures on the angles (nearly 50% in some specimens of L. glauca (Blaisdell s.n., Koelz 766) and L. stolonifera (Bordzilowski s.n., Jacobs 6140)). Ectocolpi are elongate, ranging from only slightly shorter than the polar axis in L. alutacea to distinctly shorter in L. wardii. Mean distances between the polar ends of the colpi vary from 4.8 to 10.6 pm, with marked intraspecific differences in L. glauca, L. stolonifera, and L. yunnanensis (Table 1). Intraspecific variation in this and other pollen characters will, where pertinent, be considered below in relation to proposed varieties or subspecies (see Discussion). Ectocolpi range from 2.8 to 6.0 pm wide at the equator; the sides taper to acute or narrowly rounded ends; and the colpus margin is distinct, somewhat irregular to more or less entire, unthickened, sometimes slightly raised adjacent to the endoaperture, and unconstricted at the equator (e.g., Figs. 1, 9, 16, 36, 43, 46). Relatively large processes are present over the endoapertures (e.g., Figs. 26, 32, 36, 37, 41, 46, 5 1); these vary in shape, size, and number, and some are microperforate and (or) bear supratectal spinules. The colpus membrane is otherwise essentially smooth or ornamented with smaller, scattered exine processes (e.g., Figs. 9, 14, 16, 26, 29, 31, 36, 37, 41, 46). The endoaperture is distinct to sometimes faint, equatorial, lolongate (H/W, Table l), rectangular or elliptic to irregular in outline, and included within the borders of the ectoaperture (e.g., Figs. 14 and 23). Its margin is usually unthickened. The exine is 1.5 -3.1 pm thick, semitectate, and columellate (Figs. 5, 22, 35). Exine thickness is intraspecifically variable in L. glauca and L. integrifolia (Table 1). The sexine is as thick as or thicker than the nexine. The tectum is reticulate, irregularly reticulate, or sometimes microreticulate, irregularly microreticulate, or striatomicroreticulate with vertically interlaced muri (e.g., Figs. 4, 13, 15, 17-20,24,27,28,30,45,50,52,54,55;Table 1). The muri are either smooth or ornamented with supramurial processes (spinules, granules, or transverse ridges; Figs. 2, 5, 18, 24-28, 32-34, 38, 40-42, 46-50, 52-55). The presence or absence of supramurial ornamentation appears to be intraspecifically constant (Table l), but the arrangement and type of element can vary among specimens (e.g., Figs. 33 and 34) and among grains in a single collection (Figs. 54 and 55). Although the muri in most species are predominantly simplicolumellate, duplicolumellate loci occur with varying frequency in, for example, L. brevituba (Fig. 22), L. crassifolia, L. decumbens, L. glauca, L. globosa, L. integra, L. integrifolia, L. lancilimba, L. micrantha, and L. ramalana. Muri are straight to more or less bent between junctures, sometimes incomplete and terminating in interconnected lumina (e.g., Figs. 25, 52, 54), and occasionally vertically overlapping or interwoven (e.g., L. stolonifera, Fig. 45). The mean maximum lumina diameter ranges from 0.7 to 3.4 pm. This character varies intraspecifically in L. crassifolia, L. decumbens, L. glauca, L. globosa, L. integrifolia (Figs. 33 and 34), and L. yunnanensis (Table 1). Lumina vary in outline from rounded or usually angular and unevenly polygonal to more or less irregular or elongated.


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Figs. 1-30. Scanning electron micrographs of pollen of Lagotis. Figs. 1 and 2. Lagotis integra (Forrest 14422). Fig. 1. Equatorial view. X 1400. Scale bar = 5 pm. Fig. 2. Close-up of mesocolpial exine. x5300. Scale bar = 1 pm. Figs. 3-5. Lagotis decumbens (T. Thomson s.n.). Fig. 3. Equatorial view. x 1100. Scale bar = 5 pm. Fig. 4. Close-up of mesocolpial exine. x3100. Scale bar = 1 pm. Fig. 5. Fractured mesocolpial exine. ~ 5 2 0 0 Scale . bar = 1 pm. Figs. 6 and 7. Lagotis crassifolia (Ludlow & Sherriff 9767). Fig. 6. Equatorial view. x 1100. Scale bar = 5 pm. Fig. 7. Close-up of exine. X3100. Scale bar = 1 pm. Figs. 8-10. Lagotis globosa (Ludlow & Sherriff 8499). Fig. 8. Equatorial view. X 1600. Scale bar = 5 prn. Fig. 9. Polar view. X3200. Scale bar = 1 pm. Fig. 10. Close-up of mesocolpial exine. x 5600. Scale bar = 1 pm. Figs. 11- 13. Lagotis lancilirnba (Rock 23972). Fig. 11. Subequatorial view. x 1300. Scale bar = 5 pm. Fig. 12. Polar oblique view of syncolpate grain. x 1400. Scale bar = 5 pm. Fig. 13. Close-up of mesocolpial exine. x5800. Scale bar = 1 pm. Fig. 14. Lagotis lancilimba (Rock 17956), colpus and adjacent exine. ~ 2 9 0 0 Scale . bar = 1 pm. Fig. 15. Lagotis alutacea (Rock 23364), oblique view. ~ 5 8 0 0 .Scale bar = 1 prn. Figs. 16 and 17. Lagotis rockii (Rock 22758). Fig. 16. Oblique polar view. x 1800. Scale bar = 5 pm. Fig. 17. Close-up of mesocolpial exine. ~ 5 6 0 0 .Scale bar = 1 prn. Fig. 18. Lagotis brachystachya (Przewalski 1884), mesocolpial exine. x3100. Scale bar = 1 pm. Figs. 19 and 20. Lagotis ramalana (Rock 14098). Fig. 19. Oblique view. x2100. Scale bar = 2 pm. Fig. 20. Close-up of rnesocolpial exine. x 5400. Scale bar = 1 pm. Figs. 2 1- 23. Lagotis brevituba (Licent 464 1 ) . Fig. 2 1. Close-up of mesocolpial exine. ~ 5 7 0 0 Scale . bar = 1 pm. Fig. 22. Fractured exine. Duplicolumellate at arrow. x5800. Scale bar = 1 prn. Fig. 23. Fractured exine showing internal surface of sunken ectoaperture and endoaperture. x3000. Scale bar = 1 prn. Figs. 24 and 25. Lagotis micrantha (Handel-Mazzetti 1340). Fig. 24. Close-up of exine. x5300. Scale bar = 1 pm. Fig. 25. Close-up of exine. ~ 5 6 0 0 Scale . bar = 1 pm. Figs. 26 and 27. Lagotis takedana (Coda 216). Fig. 26. Oblique polar view of colpus and mesocolpium. ~ 2 7 0 0 .Scale bar = 2 pm. Fig. 27. Close-up of exine. ~ 6 0 0 0 Scale . bar = 1 pm. Fig. 28. Lagotis takedana (Ohwi 5126). Close-up of exine. ~ 8 5 0 0 Scale . bar = 1 pm. Figs. 29 and 30. Lagotis wardii (Ward 1043). Fig. 29. Oblique view. X 1600. Scale bar = 5 pm. Fig. 30. Close-up of exine. x5600. Scale bar = 1 prn.

They are commonly reduced in size on the apocolpium (e.g., Figs. 16, 19, 29, 46) and toward the colpus (e.g., Figs. 1, 8, 14, 19, 26, 29, 32, 41, 44, 51), but the transition is gradual, and no distinctly delimited colpus border is present (see Discussion). Free-standing sculpturing elements (columellae or granules) in the lumina are evident in SEM of, for example, L. brevituba (Fig. 21), L. crassifolia (Fig. 7), L. decumbens (Fig. 4), L. glauca (Fig. 53), L. globosa (Fig. lo), L. integra (Fig. 2), L. integrifolia (Figs. 33 and 3 3 , L. micrantha (Fig. 25), L. ramalana (Figs. 19 and 20), and L. takedana (Fig. 28), but their development is intraspecifically variable (Table 1) and sometimes differs among grains within a single collection (e.g., L. micrantha, Figs. 24 and 25; L. rockii). Very small lumina are interspersed among the larger in many species (eg., Figs. 20, 27, 28, 33, 3 8 , 4 8 , 50, 54).

Discussion The pollen of Lagotis differs from that of the Selagineae and ~lobularia.It is characterized by tricolporate apeitures with smooth to sparsely granular ectocolpus membranes; lolongate endoapertures with unthickened margins included within the ectocolpi; relatively large, exinous processes over the endoapertures; and semitectate, reticulate to microreticulate exines with or without supramurial processes. Lumina are reduced in size toward the colpus, but the transition is gradual, and a sharply bounded colpus border is absent. The Selagineae differ from Lagotis in having an endoaperture with thickened margins that extends as a transverse endocolpus beneath the adjacent mesocolpia and ectocolpi that are flanked by a clearly delimited border. This border is characterized by an abrupt reduction in lumina size which defines a distinct and nearly linear boundary between the rest of the mesocolpium and a uniformly imperforate to sparsely microperforate strip on either side of the colpus (Argue 1993).

Globularia differs from Lagotis in having tecta that are spinulose-microperforate and ectocolpus membranes that are densely sculptured (Praglowski and Gyllander 1970; Punt and Marks 1991; Argue 1993). Preliminary outgroup comparisons with the Scrophularieae (Hilliard 1994 and references therein; C.L. Argue unpublished data) and the Veroniceae (Hong 1984) indicate that the transverse endocolpi with thickened margins and the distinctly delineated ectocolpus border of the Selagineae and the microperforate exines, spinulose supratectal processes, and densely sculptured ectocolpus membranes of Globularia represent derived states in these taxa (Argue 1993; C.L Argue, unpublished data). Since none of the specialized pollen features characterizing the Selagineae are found in Lagoris, and since the latter does not share the derived microperforate exine and densely sculptured colpus membrane characteristic of Globularia, pollen morphology provides no additional evidence to suppport a close relationship between Lagotis and Globularia or a transfer of Lagoris to the Selagineae from the Veroniceae, with which it appears to share a number of derived macromorphological characters (e.g., Pennell 1933; C.L. Argue, unpublished data). At the same time, there is no greater difference between the pollen grains of Globularia and Lagotis than there is between those of Globularia and Poskea (Argue 1993), a genus routinely placed with Globularia in the Globulariaceae. The pollen grains of Lagotis can be assigned more or less directly to the Paederora pollen type, one of eight pollen types that Hong (1984) recognized for tribe Veroniceae, and are similar to those of Poskea. The characters shared by these taxa, however, are of wide occurrence in the Scrophulariaceae and other angiosperms, are probably plesiomorphic, and, in the opinion of many contemporary workers (e.g., Eldredge and Cracraft 1980; Wiley et al. 1991), cannot therefore be used to indicate relationship. Although the pollen of Globularia (Praglowski and Gyllander 1970; Punt and Marks 1991; Argue 1993) differs

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Figs. 31 -55. Scanning electron micrographs of the pollen of Lagotis. Figs. 3 1- 33. Lagotis integrifolin (Morefield 5200). Fig. 3 1. Oblique view. x 1300. Scale bar = 5 pm. Fig. 32. Mesocolpial exine and colpus. X 1600. Scale bar = 5 pm. Fig. 33. Close-up of mesocolpial exine. ~ 5 8 0 0 Scale . bar = 1 pm. Figs. 34 and 35. Lagotis itztegrifolia (Cronquist 12132). Fig. 34. Close-up of exine. x5500. Scale bar = 1 pm. Fig. 35. Fractured exine. x6300. Scale bar = 1 prn. Figs. 36-38. Lagotis yutztzanensis (Rock 25160). Fig. 36. Oblique polar view. X 1200. Scale bar = 5 pm. Fig. 37. Mesocolpial exine and colpus. ~ 2 3 0 0 .Scale bar = 5 prn. Fig. 38. Close-up of exine. ~ 5 8 0 0 Scale . bar = I pm. Figs. 39-41. Lagotis korolkowi (Vasak s.n.). Fig. 39. Equatorial view. x 1000. Scale bar = 5 prn. Fig. 40. Close-up of exine. x5800. Scale bar = 1 pm. Fig. 41. Colpus and adjacent exine. X5800. Scale bar = 1 prn. Fig. 42. Lagotis korolkowi (Vvedensky s.n.). Colpus and adjacent exine. ~ 5 6 0 0 Scale . bar = 1 pm. Figs. 43-45. Lagotis stolonifera (Jacobs 6140). Fig. 43. Polar view. Unreduced apocolpial lurnina not typical of this specimen. x1500. Scale bar = 5 prn. Fig. 44. Equatorial view. x1000. Scale bar = 5 prn. Fig. 45. Close-up of mesocolpial exine. x5000,

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Scale bar = 1 pm. Figs. 46 and 47. Lagotis glauca (McIlhenny 97). Fig. 46. Oblique polar view. x2100. Scale bar = 2 pm. Fig. 47. Close-up of exine. ~ 5 7 0 0 .Scale bar = 1 pm. Figs. 48 and 49. Lagotis glnrcca (Haley s.n.). Fig. 48. Mesocolpial exine. x3100. Scale bar = 2 pm. Fig. 49. Close-up of exine. x 10 100. Scale bar = 0.5 pm. Fig. 50. Lagotis glauca (Nath 226). Close-up of exine. x5800. Scale bar = 1 pm. Figs. 5 1-53. Lagotis glauca (Stewart 19915). Fig. 51. Equatorial view. x 1100. Scale bar = 5 pm. Fig. 52. Mesocolpial exine. ~ 5 6 0 0 Scale . bar = 1 pm. Fig. 53. Close-up of muri. x 13 000. Scale bar = 0.5 pm. Figs. 54 and 55. Lagotis glauca (Ikonnikov-Galitzky 2713). Fig. 54. Close-up of exine, muri with spinules. x5800. Scale bar = 1.0 pm. Fig. 55. Close-up of exine, muri with mostly transverse ridges. x5800. Scale bar = 1.0 pm.

from that of Lagotis, it is not distinct from Hong's (1984) Wulfeniopsis type (tribe Veroniceae). These taxa share three derived pollen features: a microperforate tectum, supramurial spinules, and a sculptured colpus membrane. In terms of pollen morphology it would therefore still be more parsimonious to assume a relationship between Globularia and the Scrophulariaceae through the Veroniceae (e.g., Engler 1964) than through the Selagineae (see Introduction), as no additional changes would be necessary. The species on which Hong (1984) based both his description of the Wulfeniopsis pollen type and the new genus Wulfet7iopsis (Wulfenia amherstiana Benth.) is the same as that used by Thieret (1955) to represent Wulfenia in his study of seed morphology and which led to his placement of Wulfenia and Globularia in the same taxonomic series. The grains of L. glauca are highly variable, and Ikuse's (1956), Sokolovskaya's (1958), and Morya's (1976) descriptions of the pollen of this species fall within the range of variation observed in the present study. Data on Rock's specimen 12130 of L. brachystachya agree with Erdtman's (1952) observations on this specimen except that the present material is more fully expanded (P = 30-35 pm and E = 29-34 pm vs. P = 43 pm and E = 25 pm), and the endoapertures, ranging from distinct to only sometimes faint, are here termed colporate rather than colpor(oid)ate. The intraspecific variation observed in most characters and the prevalence of plesiomorphies preclude the application of much of the pollen data to interspecific comparisons in Lagotis. Thus, for example, the pollen evidence does not discriminate between Li's (i954) segregation of L. rockii and L. lancilimba from L. brevituba and Tsoong's (1979) reduction of both segregates to varietal status under L. alutacea (Table 1). Nevertheless, even though the incidence of homoplasy remains to be assessed, supramurial processes appear to represent a derived and intraspecifically constant character. According to Li (1954) the differences between L. micrantha and L. itztegra are variable and inconstant; the two species may be conspecific and are so treated by Tsoong (1979). Their pollen is very similar: both have supramurial transverse ridges and spinules, and both can have free-standing sculpturing elements (Fig. 2 vs. Figs. 24 and 25). Li (1954) also notes a close resemblance between L. brachystachya and L. stolonifera. However, the pollen grains of L. brachystachya have supramurial spinules and muri in a single plane (Fig. 18), whereas in L. stolonifera the muri are smooth and often vertically interwoven (Fig. 45). A number of taxa including L. minor (Willd.) Standley, L. kunawurensis (Royle) Rupr., L. cashmeriana (Royle ex Benth.) Rupr., and L. pallasii (Cham. and Schlecht.) Rupr. are recognized as distinct species by some authors and submerged in L. glauca by others. Differences in pollen

morphology between examined specimens identified by specialists as L. kunawurensis (Lowndes L1033; Stewart 19915, Figs. 51 -53), L. cashrneriana (Koelz 766; Nath 226, Fig. 50), L. pallasii (Ikonnikov-Galitzky 2713, Figs. 54 and 55) or L. minor (Blaisdell s.n.; McIlhenny 97, Figs. 46 and 47) and other specimens of L. glauca (e.g., Figs. 48 and 49) are either nonexistent or based on variable characters. The pollen grains of all of the above and all other examined specimens of L. glauca have supramurial processes. Freestanding sculpturing elements are sometimes present in specimens referred to L. minor (Blaisdell s.n.), L. cashmeriana (Nath 226), L. pallasii (Ikonnikov-Galitzky 2713), and other L. glauca (Glaser 714, Haley s.n.) as well as in those referred to L. kunawurensis, where they are most prominent; colpus length varies continuously; and the occurrence of duplicolumellate loci and mean maximum lumina diameter, both of which may differ slightly among varieties, often vary intraspecifically elsewhere in the genus (see Results). The pollen grains of the specimen referred to L. pallasii are similarly indistinct from those of L. integrifolia (Figs. 31 -35, 54, 55). The present pollen data do not therefore discriminate between the submergence of L. pallasii in L. integrifalia (Tsoong 1979) instead of L. glauca (Trautvetter 1866) or provide any additional evidence to support the reestablishment of L. minor (Standley 1931), L. pallasii (HultCn 1929), L. cashtneriana (e.g., Pennell 1943), or L. kunawurensis (e.g., Pennell 1943) as species distinct from L. glauca.

Acknowledgements I thank the curators and staff of the following herbaria who supplied requested materials for this study: BM, E, KYO, NY, TI, UC, and W. I also thank Dr. J. Doebly and Dr. A. Cholewa for use of herbarium facilities at MIN and Dr. P. Ascher and Dr. E. Stadelmann and the Department of Horticultural Science, University of Minnesota, for auxiliary research facilities. The SEM phase of this investigation was conducted in the Electron Microscope Laboratory of the Department of Genetics and Cell Biology, University of Minnesota.

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Appendix: Taxa investigated Lagotis alutncen W.W. Smith: Rock 23364 (UC). Lagotis brnchystnchyn Maxim.: Farrer & Purdom 554 (KYO), Przewalski 1884 (W), Rock 12130 (NY). Lagotis brevitubn Maxim.: Licent 4641 (W), Rock 14332 (NY). Lagotis crnssifolin Prain: Rupr.: T . Thomson s.n. (W), Lugmayer? s.n. Handel-Mazzetti 7321 (W), Ludlow & Sherriff 9767 (BM). Lagotis dec~i~nbens (W21778). Lagotis glnucn Gaertn.: Blaisdell s.n. (NY), Glaser 714 (MIN), Haley s.n. (NY), Ikonnikov-Galitzky 2713 (NY), Koelz 766 (NY), Lowndes L1033 (BM), McIlhenny? 97 (NY), Mexia 2126 (MIN), Nath 226 (NY), Stewart 19915 (NY).

Argue


Appendix (concluded) Lagotis globosa Hook. f.: Koelz 2700a (NY), Koelz 2800a (NY), Ludlow & Sherriff 8449 (BM), Stewart 9347 (NY). Lagotis itztegra W.W. Smith: Forrest 14422 (E, type). Lagotis integrijolia (Willd.) Schischkin: Cronquist 12132 & Baranova (NY), Morefield 5200 et al. (NY). Lagotis korolko~viMaxim.: Fedtschenko s.n. (NY), Kaletkina s.n. (NY), Vasak s.n. (W), Vvedensky s.n. (UC1559456 and NY), Zaprjagajev s.n. (NY). Lagotis lancilimba Li: Rock 17956 (W), Rock 23972 (UC and NY). Lagotis micrantha Hand.-Mazz.: Handel-Mazzetti 1340 (W). Lagotis ramalatza Batalin: Rock 14098 (NY). Lagotis rockii Li: Rock 22758 (NY and UC). Lagotis stolotzijera Maxim.: Bordzilowski s.n. (NY), Davis & Hedge D27643 (W), M. Jacobs 6140 (MIN), Kulzer s.n. (W17854), Th. Strauss s.n. (W), Lagotis takedana Miyabe & Tatewaki: Ohwi 5126 (KYO), collector in Japanese (TI), Yutaro Coda (or Aida) 216 (KYO). Lagotis wardii W.W. Smith: K. Ward 1043 (E, type). Lagotis yurzrzarzerzsis W.W. Smith: Forrest 23070 (UC), Handel-Mazzetti 7094? (W3717), Rock 25160 (UC).

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