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植物研究雑誌 1. Jpn. Bot. 69: 285-289 (1994) Floral Biology of Tricyrtis setouchiensis Hr. Takahashi (Liliaceae) Hiroshi TA KAHASHI Department ofBiology，Fa culty ofEducation，Gi fu University，Gi fu，50 1-11 JAPAN (Received on January 18，19 94) Tricyrtis setouchiensis has some floral-biological features distinct from other species of Tricyrtis. The flower of T. setouchiensis opens for three days，wh ich islonger than the lifespan of two days in the closely related ， species，T. affinis and T. macropoda. The male phase ofT. setouchiensis is in the first day and the female phase is in the last two days. This relatively long female phase is also distinct from the other xenogamous species of Tricyrtis with long-life flowers，be cause their male phase is in the first half of their flower-lives and their female phase is in the latter half. Perianth of T. setouchiensis is patent at apo sition of one third of the way up from the base just like T. affinis. However，T. setouchiensis has orange-yellow spots in the basa1 part of perianth. The spots seem to function as nector guides. Whereas T.正副rinishas large purple spots in the same position. Therefore there is adi fference in the spot coloration between T. setouchiensis and T. affinis. Tricyrtis setouchiensis may preserve the nectar guide coinmon to most Tricyrtis species with upright flower unlike and T. macropo，dα，wh ich appears to have no nectar guides，an d T. affinis. Introduction bloomed for more than two days，th ough the flowers Pollination and/or breeding systems emore or ofT.αがnisas well as T. macropoda live for two days. 訂 less different even among closely related species in The aim of this paper is to describe the pollination the genus Tricyrtis. Tricyrtis n ais an autogamous system of T. setouchiensis and to compare especially 仰 species unlike T. flava and T. ohsumiensis which e with that of T. affinis. 紅 outbreeders，an d the latter two are different from each other in their blooming (Takahashi 1987a). Pollina- Materials and Methods tionofT.iffinisis characterized by the refined system 正 through the patent tepals (Takahashi 1989). On the Field investigations were carried out at Mt. Koutsu- other hand pollination ofT. macropoda with recurved san，Y amakawa-cho，M ao-gun，T okushima Prefec- perian出，which is closely related to T. affinis，is fairly ture，an d at Inohana，Su moto City，(ls 1. Awaji-shima)， different from the pollination system of T. affinis Hyogo Prefecture，Ja pan. (Takahashi unpublished). Tricyrtis setouchiensis is Blooming sequence was observed for 50 flowers morphologically closely related to T. affinis，T . at Inohana in early October 1992. Insects foraging on macropoda and T. pilosα(Takahashi 1974，1 980). the flowers were observed and collected at both sites. The flower shape of T. setouchiensis is very similar UVa bsorption in the flower was examined with the to that of T. affinis. The preliminary observations of same methods used by Takahashi (1987a). T. setouchiensis，h owever，s howed that the flowers Artificial breeding experiments were performed -285ー 286 植物研究雑誌第69巻第5号平成6年10月 with the plants obtained from the Koutsu-san popula- Table 1. Insects collected on the flowers of Tricyrtis setouchiensis and their foraging objects tion and transplanted in pots at Gifu University，Gi fu (central Japan). Cross-pollination was made in the Insect Foraging object first-，se cond-and third-day flowers and self-pollina- Apidae tion in the second-day flowers. The anthers of the Bombus diversus diversus nectar (叩dpollen1l) Anthopholidae flowers for cross-pollination and apogamy testing Amegilla sp. nectar (and pollenl)) were removed before flower opening. All the experi- Halictidae Lasioglossum sp. pollen ments were carried out in an insect-free greenhouse. Syrphidae Hand pollination was done during 0900-1200 hr. 4s pecies pollen Sphingidae Germinability of the seeds obtained by the breed- 1s pecies nectar ing experiments was tested with almost the same Pollen grains were deposited on the bees only while they methods used by Takahashi (in preparation). How- l) foraged for nectar in the moming of the first day. ever，th e stratification period was 60 days，a nd the germinating seeds were counted for 60 days after incubation at 20oC，be cause seeds of T. setouchiensis Pollinators αnd their behavior Thei nsects collected germinate very well underthese conditions (Takahashi on the flowers of T. macropoda are listed in Table 1. 1986). 官lemost abundant foragers were Bombus diversus Fruit and seed set in the Koutsu-san population diversus andAmegilla sp.，th e main pollinators of this were examined in 1993. plant. Both bee species alight on the patent perianth Nu mbers of ovules and pollen grains in the flowers and suck nect Their back touches the anthers and 訂. from the lnohana population were counted with the the stigmata on the second-and third-day flowers. same methods used by Takahashi (in preparation) and However，a utogamy seems hardly to occur because the pollen/ovule ratio was calculated. Only the ovule most pollen grains are removed by the bees usually on number was counted in the Koutsu-san population. the first day. Small bees of Lasioglossum and Ceratina and some species of flies forage for pollen Results usually without touching stigmata. Howkmothes suck nectar while hovering without touching the an- Blooming sequence Although most flowers split the thers and the stigmata. perianth tip in the evening (around 1800 hr)，th 白 Flower color and UVa bsorption Thep erianth is perianth opening takes place obviously at midnight white and has small pu中lespots on the adaxial side. and they fully open by dawn of the next day (the first Large orange-yellow spots，w hich seem to be nectar day of flowering). The opening of some flowers is guides，ar e found on the adaxial side in the basal part delayed af ew hours. Most anthers dehisce at 0700- of the perianth. Purple spots訂ealso noted on the 0800 hr，bu t the style-branches are horizontally spread- filaments and the style. ing out and the stigmata are not mature yet.百lestyle- The purple and orangeyellowspots absorb almost 司 branches begin to bend down the following midnight completely UVl ight and the other p訂tsshow fairly and the stigmata are receptive and situated lower than S位ongUVa bsorption (Figs. 1a nd 2). The UVa bso中- the anther level by dawno f the second day. The flower tion pattem is similar to that of other species of the begins to close in the evening of the third day and wilts section Tricyrtis (Takahashi1984，1 989). by dawn ofthe fourth day. Breeding experiments 官leresults of breeding October 1994 Joumal of Japanese Botany Vol. 69 No. 5 287 Figs. 1-2. Flowers of Tricyrtis setouchiensis. 1，un der visible light; 2，un der UVl ight. Bar =1 c m. experiments are shown in Table 2. About 90 percent Koutsu-san population produced fruits (75.4 per- of the flowers cross-pollinated on the second or the cent). Since 29 out of the 86 fruits had already been third day fruited，wh ile about 60 percent of the flowers dehisced and some seeds appeared to have been cross-pollinated on the first day. The flowers which dispersed，th e seeds were counted in 57 capsules. The were self-pollinated on the second day produced mean seed number per fruit was 70.8 (Table 2). fruits at ar ate of about 84 percent. About 25 percent Ther esults of this experiment show that the first- of the flowers fruited autogamously. The seed num- day flowers of T. setouchiensis，w hose stigmata ap- bers per fruit averaged about 45 to 50 in the flowers pear to be immature，pr oduce many fruits in the first- cross-pollinated on the second or third day and in the day flowers when pollen grains are deposited on the self-pollinated flowers，ag ainst about 30 and 25 in the stigmata and that the flowers have ap otential to set flowers cross-po11inated in the first day and in the some fruits through autonomous self-pollination. intact flowers，re spectively. However，a utogamy hardly occurs in natural Some 86 out of 114 flowers examined in the populations because the pollinators r訂elytouch the Table 2. Results ofbreeding experiments in Tricyrtis setouchiensis. The experiments were carried out with the plants cultivated in insectfreegreenhouse. The control was examined in the Koutsu-san population. Seed set in the control was examined 姐 in 57 fruits (see text) No. of viable NO.of NO.of Fruitage seeds in afr uit samples flowers rate fruited (percent) range mean:tSD Cross-pollination in first-day flowers 57 34 59.6 0--80 31.6:t23.4 Cross-pollination in second-day flowers 53 48 90.6 0--98 49.l:t31.0 Cross-pollination in third-day flowers 48 42 87.5 5-80 44.4:t23.2 Self-pollination in second-day flowers 62 5。2 8。3.9 1-85 47.9:t21.4 Leaving emasculated flowers 51 Leaving untreated flowers 83 21 25.3 0--80 24.9:t21.2 Control 114 86 75.4 11-140 70.8:t30.1 288 植物研究雑誌第69巻第5号平成6年 10月 stigmata of the first-day flowers and most pollen contribute to total display to p01linators but also offer grains are removed on the first day by pollen foragers. an opportunity for receiving many pollen grains on Pollenlovule ratio The number of ovule and pollen the stigmata in T. setouchiensis，be cause the female grains and the pollen/ovule ratio are shown in Table 3. phase is longer than the male one. The ovule number The mean ovule number was 90.2 and 93.7 in the in the flowers of T. setouchiensis is higher than in T. populations of Inohana and Koutsu -san，re spectivel y. 4丹;nis(about 70-75; unpublished data by Takahashi). Thep ollen/ovule ratio in the Inohana population was Theo pen-pollinated flowers of the latter species pro- 1237. duced about 55 seeds on the average: about 74 percent of the ovules became seeds (Takahashi 1989). The Discussion flowers of the former species produced about 71 seeds Although the floral morphology of T. setouchien- and about 76 percent of the ovules developed to seeds. sis is very similar to that of T.イlnis，the former Ont he other hand，in the flowers of T. macropoda， species has some distinct pollination system features. which contain af ew more ovules (about 110) than T. The flower-life of three days in T. setouchiensis is setouchiensis，ab out 50 percent of ovules matured to longer than in T. affinis as well as T. macropoda which seeds (Takahashi unpublished). Therefore，th e long is also closely related to the former species; both the female phase may account for setting much seeds in latter species have two-day flowers (Takahashi 1987 a the fruits. Seed-set rates，h owever，m ay vary under and unpublished data). The different length of the different conditions such as visitation frequency of male and female phase (one and two days，r espec- pollinators，w eather，f lower density (e.g.，Di eringer tively) is another characteristic feature because the 1992). Pollination efficiency of pollinators，c ost to female phase of most species with long-lived flowers produce new flowers，n ectar volume and the like in the genus Tricyrtis is the latter half of their life should also be compared among these species to (Takahashi 1994 and unpublished data). The third- elucidate the adaptive meanings of the long-lived day flowers were frequently visited by pollinators flower in T. setouchiensis. which did not appear to discriminate them from the Theo range-yellow spots in the basal part of the younger flowers，a nd this suggests that the third-day perianth of T. setouchiensis are remarkable in evolu- flowers also secrete much nectar. Much cost should tionyimplication. They are probably the nectar 訂 be required in the long-lived flowers which secrete guide and found in most species with upright flowers nectarthroughout their lives (Southwick 1984，Pr imack in all sections of the genus Tricyrtis except for the 1985)，th ough they may be favorable for total display section Brachycyrtis which produces pendulous flow- to attract pollin剖ors(Weiss 1991). ers (Takahashi 1984，1 987a，a nd unpublished). Al- Thel ong lifespan of the flowers may not only though the main pollinators are almost the same，th e Table 3. Numbers of ovules and pollen grains and pollen/ovule ratio in Tricyrtis setouchiensis in the lnohana population and number of ovules in the Koutsu-san population Ovule no. Pollen grain no. (xl02) Pollen/ovule Population Sample no. range mean:!:SD range mean:!:SD range mean:!:SD ，;、 lnohana 30 66-110 90.2:!:12.1 696-1386 1106:t170 882-1617 1237:1:197 Koutsu-san 10 71-105 93.7:1:10.2 October 1994 Joumal of Japanese Botany Vol. 69 No. 5 289 1訂gepu中le-spots訂ein the same p訂tin T. affinis References Dieringer G. 1992. Pollinator effectiveness and seed set in whose pollination system appe紅sto be refined; its populations ofAgalinis strictifolia (Scrophulariaceae). Amer. pollinators can muche asily tak:er ewards owing to the J. Bot. 79: 1018-1023. Primack R. B. 1985. Longevity of individual f1owers. Ann. Rev. perinath morphology (Tak:ahashi，1 989). Tricyrtis Ecol. Syst. 16: 15-37. macropoda，w hose pollinators are also almost the Southwick E. E. 1984. Photosynthate allocation to f10ral nectar: same，h as none of the spots in that part and. the an eglected energy investment. Ecology 65: 1775ー1779. Takahashi H. 1974. Studies in Tricyrtis (Liliaceae) 1. Taxonomy probable nectar guide has possibly degenerated with of T. macropoda complex. Acta Phytotax. Geobot. 26: 31- 40 (in Japanese with English summary). relation to its recurved perianth (Tak:ahashi unpub- 一一一一一1980.At axonomic study on the genus Tricyrtis. Sc .i lished data). Phytogeographical data also suggest that Rep. Fac. Educ.，Gi fu Univ. (Nat. Sci.) 6: 583-635. 一一一一一1987a.Ac omparative f10ral and pollination biology T. affinis，T . macropoda and T. setouchiensis have ofTricyrtisflava Maxim.，T. nana Yatabe and T. ohsumien- appeared relatively recently (Takahashi 1987b).百lere- sis Masamune (Liliaceae). Bot. Mag. Tokyo 100: 185-203. fore，it seems to be reasonable that the orangeyellow 一一一一一1987b. Distribution of Tr・icyrtis and its 四 phytogeographical problems. Acta Phytotax. Geobot. 38: nectar guide is an ancestral character among the 123ー132.(in Japanese). species with upright flowers in Tricyrtis，a nd T. 一一一一1989.百lef10ral biology of Tricyrtis affinis Makino (Liliaceae). Plant species Biol. 4: 61-68. setouchiensis mayp reserve it unlike the other closely 一一一一一1994.Floral biology of Tricyrtis macranthopsis Masamune and T. ishiiana (Kitagawa et T. Koyama) Ohwi related species. et Okuyama var. surugensis Yamazaki (Liliaceae). Acta Phytotax. Geobot. 44 (in press). Weiss M. R. 1991. Floral colour changes as cues for pollinators. 1w ould like to thank Professor K. Yamauchi of Nature 354: 227-229. Gifu University for the、identificationof bees. 高橋弘:セトウチホトトギスの花部生態学セトウチホトトギスの花部生態学的研究を行い，ギスとよく似ている. しかし，ヤマジノホトトギホトトギス属の他の種，特にこの種に近縁なヤマスは花被の基部にある蜜標と考えられる斑紋は紫ジノホトトギスおよびヤマホトトギスと比較した. 色であるのに対して，セトウチホトトギスは直立セトウチホトトギスの花は3日間咲いていて， 2 型の花を着ける多くの種と同様に，黄櫨色である. 日間しか咲いていないヤマジノホトトギスやヤマまた，ヤマホトトギスは同じ位置にはそのようなホトトギスより花の寿命が長い.セトウチホトト斑紋認められない.蜜標と考えられる斑紋に関しギスは 1日目が雄性期で，残りの2日間が雌性期ては，これら近縁3種の中で，セトウチホトトギである.花の寿命が長いものも含めて，これまでスのみが祖先形質を保持しているのかも知れない. にわかっている他殖型の他の種は，雄性期と雌性主要なポリネーターがトラマルハナバチとコシブ期はほぼ半分ず、つで、あるので，この種はそれらとトハナパチの一種であること，花全体が紫外線を異なる.セトウチホトトギスの花は，花被が下かよく吸収すること，高い自家和合性を示すことなら約1/3のところで水平に聞き，ヤマジノホトトどはヤマジノホトトギスと同様である.