Embryology and Its Character Evolution in Staphyleaceae Author(S): Takuya Ishida and Toru Tokuoka Source: Plant Systematics and Evolution, Vol

Embryology and its character evolution in Staphyleaceae Author(s): Takuya Ishida and Toru Tokuoka Source: Plant Systematics and Evolution, Vol. 303, No. 10 (December 2017), pp. 1317-1329 Published by: Springer Stable URL: https://www.jstor.org/stable/44853800 Accessed: 06-07-2021 08:50 UTC

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This content downloaded from 86.59.13.237 on Tue, 06 Jul 2021 08:50:30 UTC All use subject to https://about.jstor.org/terms Plant Syst Evol (2017) 303:1317-1329 (jjj CrossMark https://doi.org/10.1007/s00606-017-1455-2

ORIGINAL ARTICLE

Embryology and its character evolution in Staphyleaceae

Takuya Ishida1 • Toru Tokuoka1

Received: 13 February 2017 / Accepted: 18 August 2017 / Published online: 5 September 2017 © Springer-Verlag GmbH Austria 2017

Abstract The family Staphyleaceae, which was Keywords recently Dalrympelea • Embryology • Seed coat • reorganized into the two genera Staphylea and Dalrympelea Staphylea • Staphyleaceae based on molecular phylogenetic analyses, is sister to a clade of Crossosomataceae, Guamatelaceae, and Stachyuraceae in the order Crossosomatales. In contrast to Crossosomata- Introduction ceae and Stachyuraceae, the embryology of Staphyleaceae has been scarcely studied. We carried out a literature sur- Staphyleaceae Martynov comprises the two genera vey and examined three additional species of each genus in Staphylea and Dalrympelea and 43-48 species (Simmons order to better understand the evolution of the embryological 2007), and is distributed not only in the Northern Hemi- characters in the family. Characters were nearly identical sphere of both the old and new world, but also extends south across examined species. Staphyleaceae shared most char- beyond the equator in Ecuador, Peru, Bolivia, and Southeast acters of nucellus, megagametophyte, and integuments with Asia to Papua New Guinea. The relationships of the family Stachyuraceae with the exception of several embryological have been controversial, and it had previously been placed in characters. The presence of a nucellar cap was found to be the Celastrales (Bessey 1915; Rendle 1925; Wettstein 1935; informative and supports the close relationship between Scholz 1964) or the Sapindales (Hutchinson 1926, 1973; Staphyleaceae and Stachyuraceae. We also investigated the Cronquist 1981, 1988; Takhtajan 1997). However, recent evolution of variable characters among Crossosomataceae, molecular phylogenetic studies have placed the family in Stachyuraceae, and Staphyleaceae. Staphyleaceae species the Crossosomatales, which comprises the seven families share the presence of a single archesporial cell and absence Aphloiaceae, Geissolomataceae, Strasburgeriaceae, Staphyl- of an aril as symplesiomorphies. The presence of less than eaceae, Guamatelaceae, Stachyuraceae, and Crossosomata- five parietal cells in the nucellus is a possible synapomorphy ceae (Angiosperm Phylogeny Group 2003, 2009, 2016). for the genus Staphylea , while presence of vascular bundles Staphyleaceae are sister to a clade of Crossosomataceae, in the testa is a possible synapomorphy for Staphyleaceae. Guamatelaceae, and Stachyuraceae. The remaining other Our observations support the identification of the seed coat three families form a clade in the order (Nandi et al. 1998; as mesotestal. Several variant embryological characters Savolainen et al. 2000a, b; Soltis et al. 2000). within the family are discussed. Classification within the family has also been controversial. The family previously comprised five genera, Euscaphis , Huertia, Staphylea , Tapiscia , and Turpinia

Handling editor: Louis P. Ronse De Craene. (Bentham and Hooker 1867; Cronquist 1981). Recent studies led to Tapiscia and Huertia being separated to form Ē3 Toru Tokuoka Tapisciaceae (Huerteales), and the remaining three genera tokuoka. toru @ shizuoka.ac.jp forming Staphyleaceae (Takhtajan 1997). Simmons (2002) conducted a molecular phylogenetic analysis using 4060 1 Department of Biological Science, Faculty of Science, Shizuoka University, Ohya, Suruga-ku, Shizuoka 422-8529, aligned nucleotide positions from the internal transcribed Japan spacer (ITS), 3' trnK intron, 23S-16S spacer, trnL intron,

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This content downloaded from 86.59.13.237 on Tue, 06 Jul 2021 08:50:30 UTC All use subject to https://about.jstor.org/terms 1318 T. Ishida, T. Tokuoka and the rps'2-rpl20 cells are radially elongated in Staphylea japonicaspacer and S. pin- of 27 species of the three genera. Based on nata, but arethese flattened in Dalrympelea results, grandis (= Turpinia Staphylea and Turpinia (but not the monotypie grandis). A multiplicative Euscaphis) and sclerotic mesotesta, degen- were polyphyletic, and the family was reorganized erated endotesta, and tegmenaccordingly have been described (Guérin into the two genera, Staphylea and Dalrympelea. 1901; Netolitzky 1926; Corner In 1976). On thethis basis of these scheme, the genus Staphylea comprises 23 species observations, Corner (1976, including p. 1 1) suggested that the type the Euscaphis species and some Turpinia species; of seed coat was exotestal, but thatDalrympelea this would have to be consists of the remaining 21 species of confirmed Turpiniaby further samples. Corner (1976) also observed (Simmons 2002). However, another study suggested vascular bundles in the seedthat coat, and noted that thethe vascular monotypie Euscaphis is a sister taxon to the bundles evidently clade spread from the chalaza of and form a plexusStaphylea and Turpinia (Wen et al. unpublished in the innerdata layer of the testal in mesophyll inHuang four species of et al. 2015). Embryology Staphyleaceae. has The presence offrequently vascular bundles in the testa provided useful evidence for relationships is a possible significantbetween synapomorphy for the family andand within various families (Tobe 1989). The embryology warrants further investigation, including detailed morpho- of Staphyleaceae has received some attention (Guérin logical studies, of this species. 1901; Mottier 1914; Narayana 1960; Dick- ison 1986; Matthews This paper presents a description of almost all embry-and Endress 2005). The anatropous, crassinucellate, ological characters ofand Staphyleaceae bybitegmic combining data ovule and characters of the anthers in Staphyleaavailable from earlier studies with new results. Basedtrifoliata, on S. colchica , and Dalrympe- lea montana embryological (= evidence,Turpinia we also discuss the evolution of nepalensis) were described before (Guérin 1901; embryological Narayana characters within the Crossosomatales. 1960; Dickison 1986; Matthews and Endress 2005). However, the development of the nucellus, integuments, endosperm, and embryo are scarcely known. On the other Materials andhand, methods the embryology of Stachyuraceae and Crossosomataceae has been well investigated (see table in Kimoto and Flower budsTokuoka and fruits of Staphylea bumalda DC., 5. japon-1999), although Guamatelaceae has never been icastudied (Thunb.) Simmons, and Dalrympelea embryologically. ternata (Nakai) Thus, the evolution of the embryological Simmons were collected and fixed charactersin FA A (5 parts stock within the clade of the four families including formalin; 5 parts glacial acetic acid;Staphyleaceae 90 parts 50% ethanol). could be clarified by the addition of Collectiona datathorough and developmental stages of materials exam-study of Staphyleaceae. Among the embryological ined are presented characters, in Table 1 . the presence of a nucellar cap is a feature of Alltaxonomie embryological characters were observed usingimportance in several families (Johri et al. 1992). microtomeDalrympelea sections. Materials were dehydrated through a montana and Stachyuraceae share nucellar caps r-butyl alcoholwith series, and then embeddedtwo in Paraplast withto three cell layers (Narayana 1960; Kimoto and a meltingTokuoka point of 57-58°C for microtoming. 1999), If the seeds but no information is available for the other were too hardStaphyleaceae. to be sectioned, they were softened with a The seed coat structure has also been useful in estab- mixture of 10 parts glycerol, 3 parts 10% aerosol OT, and lishing relationships between and within families (Tokuoka 90 parts water for about 1 week, following Tokuoka and and Tobe 2001, 2002, 2003; Tokuoka 2007). The structure Tobe (2001) (also Schmid and Turner 1977). Serial sec- of the seed coat has been studied in five species of the two tions 6 pm in thickness were stained with Heidenhain's genera of Staphyleaceae including Euscaphis japonica. The hematoxylin, safranin, and fast green FCF, and mounted morphology of the exotesta varied within the family; the in Entellan.

Table 1 Examined species of Staphyleaceae and collections Species Collection Developmental stages

Staphylea bumalda DC Japan. Shizuoka. Ishida 1 30428 1, 1305101, 1305221, 1 30607 1 , Youngest flower buds to mature fruits 1406011, 1407231, 1409161 (KYO)

Staphylea japonica (Thunb.) Simmons Japan. Shizuoka. Ishida 1 30508 1 , 1 305 1 3 1 , 1 3052 11,1 30527 1 , Youngest flower buds to mature fruits 1306021, 1306061, 1307011, 1310301, 1404281, 1405041, 1406241, 1407111, 1409091 (KYO) Dalrympelea ternata (Nakai) Simmons Japan. Kagoshima. Ishida 1405271, 1408181, 1506101 (KYO) Open flowers to mature fruits

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Results one enlarged megaspore mother cell below a longitudinal row of two to six parietal cells. The megaspore mother cell The examined species were nearly identical in their embryo- undergoes meiosis to produce a linear tetrad of megaspores logical characters. The following features were common to (Fig. 2d). In the megaspore tetrad, the functional chalazal all species unless otherwise stated. megaspore develops successively into a two- (Fig. 2e), four-, and eight-nucleate embryo sac. The mode of the embryo Anther and microspores sac development is of the Polygonum type, as reported by Narayana (1960) in D. montana and by Riddle (1905) in S. Stamens are borne on the inner surface of the receptacle trifoliata. An organized embryo sac has eight nuclei in seven outside of the nectariferous disk (Fig. la, b). In Staphylea cells: an egg cell, two synergids, two polar nuclei, and three bumalda , the disk is borne on the surface of the short hyp- antipodal cells (Fig. 2f). The shape of the mature embryo anthium (Fig. la). Flowers are two-carpellate in S. bumalda sac is ellipsoidal as already reported in S . trifoliata (Riddle and Dalrympelea ternata , but three-carpellate in S. japón- 1905). Neither multiple embryo sacs nor starch grains in ica (Fig. lc). The anther is tetrasporangiate (Fig. lg). The embryo sacs we observed. The antipodals degenerate before anther prior to maturation comprises five to six cell layers: or soon after fertilization. an epidermis, an endothecium, two to three middle layers, During megasporogenesis, apical epidermal cells of the and a tapetum (Fig. Id). The middle layers have a common nucellus divide periclinally to form a two- to three-celled histogenetic origin with both the endothecium and the tape- nucellar cap (Fig. 2h, i), as already reported in D. mon- tum (Fig. Id); the wall formation therefore conforms to the tana (Narayana 1960). Cells of the nucellus, except for the Basic type (Davis 1966: 10). The tapetum is glandular, and embryo sac, remain at the time of fertilization (Fig. 2g). An its cells are two-nucleate (Fig. le, f). During maturation, the obturator is not formed. A hypostase is weakly differentiated epidermal cells are persistent and flattened; the middle layers in older ovules. degenerate; and the endothecium develops fibrous thicken- ings (Fig. lh). Anther dehiscence takes place by longitudinal Integuments slits, with each slit shared by two microsporangia of a theca (Fig. lg). The characters of the type of anther wall forma- The ovule is bitegmic (Fig. 2g). The inner integument is tion, the type of the tapetum, and the number of tapetai cell initially three cell-layered and keeps its thickness until the nuclei are uncertain in D. ternata because very young flower mature embryo sac stage (Fig. 2b). The outer integument buds were not available. is initially four cell-layered (Fig. 2b), and also keeps its Meiosis in the microspore mother cell is accompanied by thickness in S. bumalda and D. ternata (Fig. 2g); however, simultaneous cytokinesis (Fig. le). A simultaneous cytoki- it slightly increased its thickness to four to five cell layers nesis is also observed in S. japónica , but in rare cases, suc- in S. japónica. Both the integuments are not vascularized cessive cytokinesis is observed in some anthers (Fig. If). until the mature embryo sac stage (Fig. 2g), but the vascular The shape of resulting tetrads is predominantly tetrahedral. bundles are initiated after the fertilization from the hilum Pollen grains are two-celled at the time of shedding (Fig. li). toward the chlaza (Fig. 4a, d, g). The endothelium is not differentiated. A micropyle is formed by both the integu- Ovules, nucellus, and megagametophyte ments as reported before by Narayana (1960) in S. bumalda and S. japónica. In D. ternata , the outer integument covers The ovule is anatropous (Fig. 2g) and crassinucellate, asthe nucellus incompletely, and the micropyle is formed by reported in D. montana and S. trif oliata (Narayana 1960; only the inner integument (Fig. 2g). Tips of both the inner Riddle 1905). Only one archesporial cell is differentiated in and outer integuments are not elongated. No aril is formed the hypodermis (Fig. 2a), although Riddle (1905) reported arising from the outer integument. that three archesporial cells can occasionally be observed in S. trifoliata. The archesporial cell divides periclinally Endosperm and embryo to form the primary parietal cell above and the sporogenous cell below (Fig. 2b). The primary parietal cell fur- Endosperm formation is of the nuclear type. Early in devel- ther divides periclinally into two to three parietal cells inopment, the endosperm comprises free nuclei, which are two Staphylea species (Fig. 2b) and six to eight cells in restricted to the periphery of the embryo sac and around a D. ternata by the stage of the mature embryo sac. Six to proembryo. Thereafter, the endosperm becomes cellular and eight parietal cells were observed in D. montana (Narayana occupies substantial space in the embryo sac. Mature seeds 1960), but in S. trifoliata three to five parietal cells were thus have copious endosperm around the embryo. Neither formed (Riddle 1905). The sporogenous cell develops into the endosperm haustorium nor perisperm is formed. a megaspore mother cell (Fig. 2b, c). Thus, ovules have

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«Fig. 1 Section of flowers also parenchymatous. and Asdevelopment the seed develops, all the cells ofof anther and microspores in Staphyleaceae. a, d, the tegmene, g degenerate Staphylea and disappear. bumalda ; b-d, f, h, i S. japón- ica. a, b Longitudinal section (LS) of a young flower, c Transverse section (TS) of a young flower, d TS of a young anther showing the development of the anther Summary of embryologicalwall, featurese Meiosis of Staphyleaceae in microsporangium showing simultaneous cytokinesis. Arrows indicate the nuclei of tapetum. f Meiosis in microsporangium Anther tetrasporangiate; showing anther wall five to sixsuccessive cells thick, cytokinesis. Arrows indicate the nuclei of tapetum. g TS of a mature anther, h TS of a anther wall formation of the Basic type; both epidermis and mature anther wall, i Mature pollen grain with a generative nucleus (arrow) stained with fibroushematoxylin. endothecium persistent; two toScale three middle layersbars 0.5 mm in a; 1 mm in b, c; 10 pm in d, i; 20 ephemeral;pm andin tapetum e, glandularf; 200 with two-nucleate pm cells.in g; 50 pm in h. ep epidermis, et endothecium, mime Cytokinesis in themicrospore microspore mother cell simultaneous; mother cell, ml middle layer, t tapetum predominant shape of microspore tetrads tetrahedral; pollen grains two-celled when shed. We did not examine embryogenesis in detail in this Ovule anatropous and crassinucellate; one archesporial study, but fragmentary observations of early embryogen- cell dividing into the primary parietal cell and the sporog- esis indicate that it proceeds normally to form a globular enous cell; the sporogenous cell differentiating into the proembryo which eventually develops into a dicotyledon- megaspore mother cell; the thickness of the parietal tis- ous embryo. The suspensor is short. The embryo in mature sue lying above the megaspore mother cell two to six cell seeds is straight and has two equal-sized, non-chlorophyllous layers; a tetrad of megaspores linear; functional chalazal cotyledons. megaspore, developing into an eight-nucleate Polygonum type embryo sac; antipodal cells ephemeral. A two to three Seed cell-layered nucellar cap formed; no obturator formed; a hypostase formed. Ovules with multiple embryo sacs absent, Mature seeds are laterally flattened to be ellipsoidal with- and nucellar tissue in mature ovule remaining. out any appendages such as arils or wings. The seed coat is Ovule bitegmic; inner integument (ii) three cells thick; formed by both the testa (i.e., developed outer integument) outer integument (oi) four cells thick; ii without vascular and the tegmen (i.e., developed inner integument). The bundles; vascular bundles differentiated in oi after fertili- testa increases in thickness after fertilization, resulting in a zation; micropyle formed only by ii or by both ii and oi; thick testa composed of 12 to 16 cell layers (Fig. 3a-i). The neither endostome nor exostome elongated; endothelium not exotesta is not multiplicative, but its structure varies among formed. species. In S. bumalda , the cells remain cuboidal and accu- Endosperm formation of the nuclear type; embryogen- mulate tannins (Fig. 4b, c). In S. japónica , the cells elongate esis unknown; endosperm haustorium not formed; suspensor radially and then enlarge, but the cells lose their contents short. Mature seeds ellipsoidal, exarillate; embryo in mature and remain thin-walled (Fig. 4e, f). In D. ternata , cells seed straight, with two symmetrical, non-chlorophyllous cot- become spheroidal and tanniniferous (Fig. 4h, i). The mes- yledons. Endosperm persistent in mature seed; perisperm otesta is thick with more than eight to ten cell layers in all absent; both testa and tegmen increasing their thickness after three examined species. The cells of the mesotesta become fertilization; testa vascularized; cells of exotesta cuboid, slightly enlarged, and then thick- walled and pitted in mature radially elongated, or spheroidal; mesotesta extremely thick- seeds (Fig. 3a-i). The most specialized mechanical tissue of walled, pitted; endotesta multi-layered, parenchymatous; the mature seed coat is thus constructed by the mesotesta, exo-, meso-, and endotegmen parenchymatous and crushed; and therefore the seed coat of Staphyleaceae is mesotestal. seed coat structure "mesotestal." The endotesta is multiplicative and two to three cell layers thick (Fig. 3b, c, e, f, h, i). The cells of the endotesta remain parenchymatous in the mature seed coat. The procambial Discussion bundles in the mesotesta are initiated after fertilization. The vascular bundles are extended from a hilum toward the cha- Comparison and evolution of embryological characters laza (Fig. 4a, d, g). The presence of vascular bundles in the testa is more easily confirmed in mature seeds. Table 2 summarizes embryological data for Staphyleaceae, The tegmen also increases in thickness after fertilization based on the three species of Staphylea and Dalrympelea , and becomes 12 to 14 cell-layered in S. bumalda and D. together with already published data for Crossosomataceae ternata and five to six cell-layered in S. japónica. The cells and Stachyuraceae. The order Crossosomatales comprises of the exotegmen are elongated only longitudinally and par- seven families, and the relationships among the families enchymatous. The cells of the meso- and endotegmen are have already been clarified viz. Staphyleaceae, Crossoso- mataceae, Guamatelaceae, and Stachyuraceae form a clade,

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Fig. 2 Development e Two-nucleate of ovule andembryo embryo sac. sacf Mature in Staphyleaceae. embryo sac. a, g f, LS of a mature h Staphylea bumalda ovule, ;h, b, id, LS e, of i S.a tipjapónica of the ; c, nucellus g Dalrympelea showing ternata. nucellar cap. Sale bars a Longitudinal 50section pm in (LS) a-c, of g; young 20 pm ovule in d-f, with h, archesporiali. ant antipodals, cell. b, ar archesporial c LS of a developed cell, eg ovule egg cell,with ii megaspore inner integument, mother mmccell. dmegaspore LS of the mother cell, nc nucellus with nucellarmegaspore cap, tetrad. oi outer Arrows integument, indicate po fourpolar megaspores.nuclei, syn synergid

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Fig. 3 Young seed andbundle. seed Scale coat bars in 0.5Staphyleaceae. mm in a, g; 50a-c pm Staphylea in b, c, e, h, i; 300 pm in d; bumalda; d-f S. japónica; 100 pm g-i inDalrympelea f. ents endotesta, ternata, exts a, exotesta,d, g Longitu- mts mesotesta, ts testa, vb dinal section of a young vascular bundle seed, b, e, h LS of testa of a young seed, c, f, i Transverse section of testa of a young seed showing the vascular

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Fig. 4 Mature verse seed section and seed of coattesta inof Staphyleaceae.a mature seed showinga-c Staphylea the vascular bundle. bumalda; d-f ScaleS. japónica; bars 1 mm g-i inDalrympelea a, d, g; 50 pm ternata, in b, c; a, 100 d, pmg Mature in e, f, h, i. ch cha- seed coat from laza, the ents inside endotesta, showing exts exotesta,vascular hi bundles hilum, mstsextending mesotesta, ts testa, from the hilum vb vascular bundle toward the chalaza. Endosperm and cotyledon were removed, b, e, h Longitudinal section of a mature seed, c, f, i Trans-

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Table 2 A summary of embryological data of Staphyleaceae, Stachyuraceae, and Crossosomataceae

Taxon Staphyleaceae Stachyuraceae Crossosomataceae

Anther and microspores Number of sporangia 4 4 4 Thickness of anther wall (4-)5-6a 5-6 8-9 Type of wall formation Basic Basic NA Anther epidermis Persistent, flattened Persistent Persistent Endothecium Fibrous Fibrous Fibrous Middle layers Crushed Crushed NA Tapetum Glandular Glandular Glandular Number of nuclei in tapetai cell 2 2, sometimes 1 Several Cytokinesis in meiosis Simultaneous0 Simultaneous Simultaneous Shape of microspore tetrads Tetrahedral Tetrahedral Tetrahedral and decussate Mature pollen 2-celled 2-celled 2-celled Ovules, nucellus, and megagametophyte Ovular orientation Anatropous Anatropous Campylotropous Obturator Not formed Not formed NA Hypostase Formed Formed Formed Number of archesporial cells 1, 3C 2 or 3, rarely 1 Several Nature of nucellus Crassinucellate Crassinucellate Crassinucellate Thickness of parietal tissue 2-3(-5)/6-8 6-8 6-7 Mode of embryo sac formation Polygonum type Polygonum type Polygonum type Shape of mature e.s. Oblong Oblong Curved Multiple e.s. No No No Antipodal cells Ephemeral Ephemeral Ephemeral, 5-6 celled Starch grains in e.s. Absent Absent NA Nucellar cap Formed, 2-3 celled Formed, 2-3 celled NA Nucellarbeak Not formed Not formed NA Nucellar tissue in mature ovule Remaining Remaining Remaining Integuments Number of integuments 2 2 2 Thickness of ii (early stage) 3 2-3 NA Thickness of ii (late stage) 3 4-5 c.4 Thickness of oi (early stage) 4 2-3 NA Thickness of oi (late stage) 4-5 4-5 7 Vascular bundles in ii Absent Absent Absent Vascular bundles in oi Present Absent Absent Micropyle formation Both ii and oi/only ii Both ii and oi Both ii and oi Endostome Not elongated Elongate NA Exostome Not elongated Elongate NA Endothelium Not formed Not formed NA Development of endosperm and embryo Mode of endosperm formation Nuclear Nuclear Nuclear Haustorial endosperm Not formed Not formed NA Type of embryogeny NA Solanad type Onagrad type Suspensor Short Short NA Seed and seed coat Shape Ellipsoidal Ellipsoidal, slightly curved Reniform Aril/Wing Not formed Formed Formed Endosperm in mature seed Remaining Remaining Remaining Perisperm Absent Absent NA

Embryo curvature

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Table 2 (continued)

Taxon Staphyleaceae Stachyuraceae Crossosomataceae

Embryo (chlorophyllous or not) Not chlorophyllous Not chlorophyllous NA Cotyledons Straight Straight Curved Embryo of dicots Symmetrical Symmetrical Symmetrical Seed coat Seed type Mesotestal Exotestal Testal Thickness of seed coat 12-16 5-6 4-5 cells thick Cells of exotesta 1 cell-layered, cuboidal, tan- 2 cell-layered, sclerotic, pitted, e niferous/radially elongate, radially elongated with sinuous parenchymatous, tanniferous/ anticlinal walls spheroidal, tanniferous Cells of mesotesta Over 10 cell-layered, thick- 1-2 cell-layered, sclerotic, pit- e walled, pitted ted, tangentially elongated Cells of endotesta 2 cell-layered, parenchymatous 1 cell-layered, sclerotic, tangen- e tially elongated Cells of exotegmen Longitudinally elongated, 1 layered, thin, tangentially Unspecialized crushed elongated Cells of mesotegmen Unspecialized, crushed Crushed Unspecialized Cells of endotegmen Unspecialized, crushed Crushed Fibrous Reference Corner (1976), Dickison (1986), Corner (1976), Kimoto and Brandegee (1899), Kapil Guérin (1901), Matthews and Tokuoka (1999), Mathew and (1970), Kapil and Vani Endress (2005), Mottier (1914), Chaphekar (1977), Matthews (1963), Mason (1975), Narayana (1960), Netolitzky and Endress (2005), Mauritzon Matthews and Endress (1926) and Riddle (1905) (1936) and Sato (1976) (2005), Mauritzon (1939) and Thorne and Scogin (1978) NA No information available aNarayana (1960) reported the four cell-layered anther wall Simultaneous cytokinesis was observed in Staphylea japónica , but in rare cases successive cytokinesis was also observed in some anthers c Riddle (1905) reported three archesporial cells in Staphylea trifoliata dVascular bundles were initiated after fertilization cCrossosoma has a four to five cell-layered seed coat with sclerotic cells developed from the outer integument, but the origin of each cell layer is still uncertain (Kapil and Vani 1963; Kapil 1970) and the remaining three families also form a clade (Stevens three families share all anther and microspore characters. 2001 onward). We compared the embryological character Staphyleaceae also share all characters of ovule, nucellus, states among the families within the former clade in Table 2,megagametophyte, and integuments with Stachyuraceae, except Guamatelaceae for which embryological information with the exception of the numerous embryological characters was not available. All embryological features are consist- discussed below. Among the embryological characters, the ent across species within the family except for the type ofpresence of the two- to three-celled nucellar cap should be cytokinesis in meiosis, thickness of parietal cells in nucel- emphasized, which Staphyleaceae share with Stachyuraceae. lus, and the morphology of exotesta. This embryological The presence of the nucellar cap is a feature of taxonomie study supports the close relationship between Staphylea importance in several families (Johri et al. 1992), and prob- and Dalrympelea. The previous classification suggested ably supports the close relationship between Staphyleaceae that Tapiscia and Huertia were included in Staphyleaceae and Stachyuraceae. Further embryological studies of the (Bentham and Hooker 1867; Cronquist 1981). However, other Crossosomatales are, however, necessary in the future. Staphyleaceae are restricted to Staphylea and Dalrympelea Staphyleaceae are distinguished from Stachyuraceae and on the basis of the recent molecular phylogenetic analysis Crossosomataceae by several embryological characters. (Simmons 2002) and floral anatomy (Dickison 1986), and Staphyleaceae possess only one archesporial cell, while this embryological study supports this view. Stachyuraceae and Crossosomataceae possess several. The Staphyleaceae also share most embryological characters parietal cells of the nucellus form two to three layers in the with Crossosomataceae and Stachyuraceae, and similarity istwo examined species of Staphylea and three to five layers greater with Stachyuraceae than Crossosomataceae. These in S. trifoliata (Riddle 1905), on the other hand, more than

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Less than five parietal layers i Staphylea bumalda g Presence of vascular Absence of I I g bundles in testa an aril ■ I w I ļ I Staphylea japónica ^ JS Presence of Dalrympelea ^ nucellar cap

KmlarcMspoi.1^

Guamatelaceae

Crossosomatales families

Fig. 5 Phylogenetic tree showing relationships of Staphyleaceae, Stachyuraceae, Crossosomataceae and Guamatelaceae, and an evolution of several significant embryological characters. The tree is based on Stevens (2001 onward) and Simmons (2002)

four to eight layers in Stachyuraceae, Crossosomataceae, the and other Crossosomatales. Further embryological studies Dalrympelea. In Staphyleaceae, vascular bundles are devel-of the other Crossosomatales such as Crossosomataceae and oped in the testa after fertilization, but no vascular bundlesGeissolomataceae are necessary to construct a clearer evo- are present in Stachyuraceae and Crossosomataceae. Neither lutionary scenario for each of the characters. the exostome nor endostome is elongated in Staphyleaceae, The seed coat structure has successfully been used to but both are elongated in Stachyuraceae. Regarding the establish seed relationships between and within various families coat structure, an aril is absent in Staphyleaceae but (Tokuoka pre- and Tobe 2001, 2002, 2003; Tokuoka 2007). The sent in Stachyuraceae and Crossosomataceae. The type structure of of the testa in Staphyleaceae is different from that seed coat is mesotestal in Staphyleaceae, but exotestal in Stachyuraceae. in In Staphyleaceae, the exotesta remains Stachyuraceae. The mesotesta is multiplicative and six single-layered, to the mesotesta is multiplicative and more than twenty-six cell layers thick in Staphyleaceae, but not eightmulti- cell layers thick, and the endotesta is also multiplica- plicative in Stachyuraceae. The endotesta is multiplicative tive and remains thin- walled. In Stachyuraceae, the exotesta and two to three cell-layered, but remains single-layered is two in cells thick, the mesotesta is one or two cell-layered, Stachyuraceae. and the endotesta is single-layered and sclerotic. The evolu- We mapped the embryological character states within tion of these characters of the testa is still uncertain as no Staphyleaceae on the molecular phylogenetic tree derived information by is available for the other Crossosomatales. Seed Simmons (2002) using the other Crossosomatales families coat anatomy for these Crossosomatales also requires fur- as an outgroup, and inferred the character evolution (Fig.ther study.5). In Staphyleaceae, Corner (1976, p. 1 1) described Staphyleaceae shares the nucellus with a single archesporial the type of the seed coat as exotestal with sclerotic mes- cell with the outgroup as a symplesiomorphy, while multiple otesta (=exo-mesotestal) based on examination of the four archesporial cells are synapomorphic for Stachyuraceae species and of the family, including S . japónica (=Euscaphis Crossosomataceae (no information was available for japónica).Gua- Our examination, however, showed that the cells matelaceae). The less than five parietal cells of the nucel-of the exotesta of the three examined species are only tan- lus are possibly a synapomorphy for the genus Staphylea. niniferous and remain thin-walled. Our results support the Stachyuraceae, Crossosomataceae, and Dalrympelea interpretation share that the seed coat is mesotestal. six to eight parietal cells as a probable symplesiomorphy, Several embryological characters varied within the although this is still unknown for the outgroup. The presence family. The shape of the exotestal cells is cuboidal in S. of vascular bundles in the testa is a possible synapomorphy bumalda , radially elongated in S. japónica , and spheroidal in for Staphyleaceae, although no information was available D. temata. for This character may have diverged independently the outgroups. However, absence of vascular bundles inin thethe different species within the family, driven by seed testa is very common in angiosperms. The absence of dispersalan aril and pericarp morphology. Successive cytokinesis is a possible synapomorphy for the family. The polarity in meiosis of was observed in rare instances in a few anthers the morphological character of the endostome and exostome in S. japónica , while simultaneous cytokinesis is present in remains uncertain, because no information is available for

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This content downloaded from 86.59.13.237 on Tue, 06 Jul 2021 08:50:30 UTC All use subject to https://about.jstor.org/terms 1328 T. Ishida, T. Tokuoka most other Mathewanthers. CJ, Chaphekar M (1977) Development of femaleThis gameto- character may be subject to easy variation in phyteS. and embryogeny japónica. in Stachyurus chinensis. Phytomorphol- ogy 27:68-79 Matthews ML, Endress PK (2005) Comparative floral structure and Acknowledgement systematics in Crossosomatales I am (Crossosomataceae, grateful Stach- to two anonymous reviewers and Louis P. Ronse Deyuraceae, Staphyleaceae,Craene Aphloiaceae, Geissolomataceae, (E) for helpful comments on the manuscript. This study was Ixerbaceae, supported Strasburgeriaceae). Bot J Linn Soc 147:1-46. by a Grant-in-Aid for Scientific Research from the Japan doi: 10. 1 1Society 1 1/j. 1095-8339.2005.00347.X for the Promotion of Science (25440205). Mauritzon J (1936) Zur Embryologie einiger Parietales-familien. Compliance with Svensk Bot Tidskr 30:79-1ethical 13 standards Mauritzon J (1939) Contribution to the embryology of the orders Conflict of interest Rosales and Myrtales. Acta Univ The Lund 35:1-121 authors declare that they have no conflict of interest. Mottier DM (1914) Mitosis in the pollen mother-cells of Acer negundo L. and Staphylea trifoliata L. Ann Bot [König & Sims] 28:115-133 Nandi OI, Chase MW, Endress PK (1998) A combined cladistic analy- References sis of angiosperms using rbcL and non-molecular data sets. Ann Missouri Bot Gard 85: 137-212. doi: 10.2307/2992003 Angiosperm Phylogeny Group (2003) An update of the Angio- Narayana LL (1960) Embryology of Staphyleaceae. Curr Sci sperm Phylogeny Group classification for the orders and 29:403-404 families of flowering plants. Bot J Linn Soc 141:399-436. Netolitzky F (1926) Anatomie der Angiospermen-Samen. In: Linsbauer doi:10.1046/j.l095-8339.2003.t01-l-00158.x K (ed) Handbuch Der Pflanzenanatomie, Abt. II, Teil 2, Bd. 10, Angiosperm Phylogeny Group (2009) An update or the Angio- pp 194-195 sperm Phylogeny Group classification for the orders and fami- Rendle AB (1925) The classification of flowering plants, vol. 2. Uni- lies of flowering plants: APG III. Bot J Linn Soc 161:105-121. versity Press, Cambridge doi: 10. 1 1 1 1/j. 1095-8339.2009 .00996.x Riddle LC (1905) Development of the embryo sac and embryo of Angiosperm Phylogeny Group (2016) An update of the Angiosperm Staphylea trifoliata . Ohio Naturalist 5:320-325 Phylogeny Group classification for the orders and families of flow- Sato Y (1976) Embryological studies on Stachyurus praecox and its ering plants: APG IV. Bot J Linn Soc 181:1-20. doi: 10. 1111/ variety. Sci Rep Tohoku Univ Fourth Ser Biol 37:131-138 boj. 12385 Savolainen V, Chase MW, Hoot SB, Morton CM, Soltis DE, Bayer C, Bentham G, Hooker JD (1867) Genera plantarum, I. Reeve, London Fay MF, de Bruijn AY, Sulllivan S, Qiu Y-L (2000a) Phyloge- Bessey CE (1915) The phylogenetic taxonomy of flowering plants. Ann netics of flowering plants based on combined analysis of plastid Missouri Bot Gard 2:109-164. doi: 10.2307/2990030 atpB and rbcL sequences. Syst Biol 49:306-362. doi: 10. 1093/ Brandegee TS (1899) New species of western plants. Bot Gaz 27:444- sysbio/49.2.306 457. doi: 10. 1086/327855 Savolainen V, Fay MF, Albach DC, Backlund A, van der Bank M, Corner EJH (1976) The seeds of dicotyledons. Cambridge University Cameron KM, Johnson SA, Lledó MD, Pintaud J-C, Powell M, Press, Cambridge Sheahan MC, Soltis DE, Soltis PS, Weston P, Whitten WM, Wur- Cronquist A (1981) An integrated system of classification of flowering dack KJ, Chase MW (2000b) Phylogeny of the eudicots: a nearly plants. Columbia University Press, New York complete familial analysis based on rbcL gene sequences. Kew Cronquist A (1988) The evolution and classification of flowering Bull 55:257-309. doi: 10.2307/41 15644 plants, 2nd edn. The New York Botanical Garden, Bronx Schmid R, Turner MD (1977) Contrad 70, an effective softner of Davis GL (1966) Systematic embryology of angiosperms. Wiley, New herbarium material for anatomical study. Taxon 26:551-552. York doi: 10.2307/1219648 Dickison WC (1986) Floral morphology and anatomy of Staphyl- Scholz H (1964) Staphyleaceae. In: Melchior H (ed) A Engler s Syl- eaceae. Bot Gaz 147:312-326. doi: 10. 1086/337598 labus der Pflanzenfamilien, vol. 3, part 5. Wilhelm Engelmann, Guérin P (1901) Dévéloppment de la graine et en particulier du tégu- Leipzig ment séminal de quelques Sapindacées. J Bot (Morot) 15:336-362 Simmons SL (2002) A molecular phylogenetic investigation of the Huang Y-J, Liu Y-S, Wen J, Quan C (2015) First fossil record of Staphyleaceae (DC.) Lindl.: with implications for its taxonomy Staphylea L. (Staphyleaceae) from North America, and its biogeo- and biogeography. PhD Thesis, University of Texas, Austin graphic implications. PI Syst Evol 301:2203-2218. doi: 10. 1007/ Simmons SL (2007) Staphyleaceae. In: Kubitzki K (ed) Flowering S00606-015-1224-Z plants. Eudicots. The families and genera of vascular plants, IX. Hutchinson J (1926) The families of flowering plants: dicotyledons. Springer, Berlin, pp 440-445 Macmillan, London, p 328 Soltis DE, Mort ME, Soltis PS, Albach DC, Zanis M, Savolainen V, Hutchinson J (1973) The families of flowering plants, 3rd edn. Clar- Hahn WH, Hoot SB, Fay MF, Axtell M, Swensen SM, Price LM, endon, Oxford Kress WJ, Nixon KC, Farris JS (2000) Angiosperm phylogeny Johri BM, Ambegaokar KB, Srivastava PS (1992) Comparative embry- inferred from 18S rDNA, rbcL , and atpB sequences. Bot J Linn ology of Angiosperms. Springer, Berlin Soc 133:381-461. doi: 10.1 1 1 1/j. 1095-8339. 2000.tb01588.x Kapil RN (1970) Crossosomataceae in symposium comparative embry- Stevens PF (2001 onwards) Angiosperm phylogeny website. Version ology of angiosperms. Bull Indian Natl Sci Acad 41 :63-68 12, July 2012 [and more or less continuously updated since]. Kapil RN, Vani RS (1963) Embryology and systematic position Availableor at: http://www.mobot.org/MOBOT/research/APweb/. Crossosoma californicum Nutt. Curr Sci 32:493-495 Accessed 17 Jan 2017 Kimoto Y, Tokuoka T (1999) Embryology and relationships of Stachy- Takhtajan A (1997) Diversity and classification of flowering plants. urus (Stachyuraceae). Acta Phytotax Geobot 50:187-200 Columbia University Press, New York Mason CT Jr (1975) Apacheria chiricahuensis : a new genus and Thorne spe- RF, Scogin R (1978) Forsellesia Greene (Glossopetalon Gray), cies from Arizona. Madoroño 23:105-108 a third genus in the Crossosomataceae, Rosineae, Rosales. Aliso 9:171-178. doi: 10.5642/aliso. 19780902.03

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This content downloaded from 86.59.13.237 on Tue, 06 Jul 2021 08:50:30 UTC All use subject to https://about.jstor.org/terms Embryology of Staphyleaceae 1329

Tobe H (1989) The embryology Tokuoka T, Tobe H (2002) Ovules andof seeds angiosperms:in subfamily Euphor- its broad applica- tion to the systematic bioideae and (Euphorbiaceae): evolutionary structure and systematic implications. study. Bot Mag (Tokyo) 102:351-367. doi:10.1007/BF02488572 J PI Res 115:361-374. doi:10.1007/sl0265-002-0047-5 Tokuoka T (2007) Molecular phylogenetic analysis of Euphorbi- Tokuoka T, Tobe H (2003) Ovules and seeds in Acalyphoideae aceae sensu stricto based on plastid and nuclear DNA sequences (Euphorbiaceae): structure and systematic implications. J PI Res and ovule and seed character evolution. J PI Res 120:51 1-522. 1 16:355-380. doi:10.1007/sl0265-003-01 16-4 doi: 10. 1007/S10265-007-0090-3 Wettstein R (1935) Handbuch der systematischen Botanik. Franz Deu- Tokuoka T, Tobe H (2001) Ovules and seeds in subfamily Phyllan- ticke, Wien thoideae (Euphorbiaceae): structure and systematic implications. J PI Res 114:75-92. doi :10.1007/PL000 13970

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