Change of bract size and color 苞の大きさや色の変化

Lavandula stoechas

ラベンダー属は約36種がマクロネシア、地中海盆地、北アフリカ、北東アフリカ、南西アフリカ、南西アジア、アラビア半島、インド中部と南部に分布する(Harley et al. 2004)。Lavandula stoechasは地中海周辺に野生する(Upson and Andrews 2004)。

Lavandula includes approximately 36 species, which are distributed in Macronesia, Mediterranean basin, North and North East Africa, South West Africa, South West Asia, Arabian Peninsula, and Central and south India (Harley et al. 2004). Lavandula stoechas is distributed in Mediterranean regions (Upson and Andrews 2004).

Harley, R.M., Atkins, S., Budantsev, A.L., Cantino, P.D., Conn, B.J., Grayer, R., Harley, M.M., de Kok, R., Krestovskaja, T., Morales, R., Paton, A.J., Ryding, O., and Upson, T. 2004. Labiatae. In Kubitzki, K. ed. The Families and Genera of Vascular Plants VII: Kadereit, J.E. ed. Flowering Plants. Dicotyledons: Lamiales (except Acanthaceae including Avicenniaceae). Springer, Berlin.

Upson, T. and S. Andrews 2004. The Genus Lavandula, Botanical Magazine Monograph. Royal Botanic Gardens, Kew.

Lavandula stoechas


A bract subtends five flowers to one flower depending on its position in an inflorescence.

Lavandula stoechas

花序の先端側の4枚の苞は、他の苞より大きく綺麗になる。ガガイモ属(Wilson and Price 1977)、ベゴニア属 (Schemske and Agren 1995)、ヒエンソウ属 (Waser and Price 1991)、スミレ科のヒバツス属 (Augspurger 1980)などで訪花昆虫を誘引するコストを増やすと、媒介昆虫の数も増えているという研究結果が報告されている。しかし、Lavandula stoechasの場合は、野外集団で、花弁状苞を取り除いた個体と取り除いていない個体を比較しても、両者で訪花昆虫数、種子数に統計的に有為な違いは見られなかった(Herrera 1997)。このことから、Lavandula stoechasの花弁状苞は、訪花昆虫が十分にいる通常状態ではなく、訪花昆虫が少ない、あるいは、少数の植物体だけが生育している場合などに適応的なのかもしれない(Herrera 1997)。

Most distal four bracts are larger and more colorful than other bracts. Several reports showed the positive relationships between costs in advertisement and pollinator visitations in Asclepias (Wilson and Price 1977), Begonia (Schemske and Agren 1995), Delphinium (Waser and Price 1991), Hybanthus (Augspurger 1980), and so on (Gori 1983). However, the removal of large and colorful bracts in Lavandula stoechas did not significantly reduce pollinator visitation rates and fecundity in wild populations, implying that those bracts function in unusual conditions, including extremely low plant density (Herrera 1997).

Augspurger, C. K. 1980. Mass-flowering of a tropical shrub (Hybanthus prunifolius): influence on pollinator attraction and movement. Evolution 34:475-488.

Gori, D. F 1983. Post-pollination phenomena and adaptive floral changes. Pages 31-49 in C. E. Jones and R. J. Little, editors. Handbook of experimental pollination biology. Sci- entific and Academic Editions, New York, New York, USA.

Herrera J. 1997 The role of colored accessory bracts in the reproductive biology of Lavandula stoechas. Ecology 78, 494–504.

Stearn, W.T. 1992 Botanical Latin 4th ed. Timber Press, Oregon.

Schemske, D. W., and J. Agren. 1995. Deceit pollination and selection on female flower size in Begonia involucrata: an experimental approach. Evolution 49:207-214.

Waser, N. M., and M. V. Price. 1991. Outcrossing distance effects in Delphinium nelsonii: pollen loads, pollen tubes, and seed set. Ecology 72:171-179.

Willson, M. F, and P. W. Price. 1977. The evolution of in- florescence size in Asclepias (Asclepiadaceae). Evolution 31:495-511.

Lavandula stoechas


No flowers are formed at the axils of large bracts. If the size of a primordium to form a bract and flower (s) is limited, a primordium can make only a bract and no flowers when a bract becomes larger. On the other hand, a lack of flower initiation might result in the extra space for a large bract.

Lavandula dentata

Lavandula dentataは、地中海地域に分布する (Upson and Andrews 2004)。先端の約10枚の苞が大きく、カラフルになる。

Lavandula dentata is distributed in the Mediterranean region (Upson and Andrews 2004). Lavandula dentata forms approximately ten large bracts in comparison to usually four in Lavandula stoechas.

Upson, T. and S. Andrews 2004. The Genus Lavandula, Botanical Magazine Monograph. Royal Botanic Gardens, Kew.

Lavandula dentata

花序の基部側の苞は約3個の花を抱き、中央付近の苞は1個、先端近くの苞は花を抱かない。Lavandula stoechas Lavandula dentata の違いはどのような発生の仕方の違いによって生じているのだろうか。

More basal large bracts subtend approximately three flowers, middle ones one flower, and distal three or four bracts do not any flowers. What is the developmental difference between Lavandula stoechas and Lavandula dentata?

Salvia virdis “Marble Arche”

Salvia virdisでは、花序先端部分の苞が花を着ける苞より大きくなって紫に色づくが、苞の腋には花がつかない。これら以外の苞は、緑色で腋に花を付ける。このような違いはどのように発生過程を変えることによって引き起こされているのだろうか。進化の過程で全く新しいものを作り出すことはほとんどなく、体のどこか別の場所で使ってた発生機構、遺伝子系を用いている場合が多い。色の付いている花弁の遺伝子系を流用したのだろうか。では、紫色の苞が緑の苞よりも大きくなる点はどうだろう。どうやって特定の器官を大きくするのだろうか。

Large and colorful bracts are also observed in Salvia and do not subtend flowers. Basal bracts are greenish and how these large and colorful bracts acquired the developmental system during the evolution. At least,

Genetic regulatory network for color pigmentation appears to be coopted from that used in petals, while it is difficult to hypothesize the evolution of the additional growth.

Houttuynia cordata


In the pseudanthium of Houttuynia cordata in the Piperaceae, basal four flowers are subtended by large and white bracts, while other flowers are by tiny and white bracts. This suggests that bracts of basal four flowers evolved to become larger, or bracts except basal four to become smaller. Again, molecular and developmental mechanisms to regulate the organ size is not well understood and we do not know what change of genetic regulatory networks caused such evolution.

カテゴリー: 5.05.04.Piperales.コショウ目,シソ目, Allocation between organs 器官間の配分, heterophylly 異型葉性, Organ size 器官サイズ, pseudanthium 偽花 | Change of bract size and color 苞の大きさや色の変化 はコメントを受け付けていません。

Reduction in leaf morphology 葉形態の退化

Asplenium septentrionale

Asplenium septentrionale


Lamina is reduced and  a few sporangia are formed, likely because of draught tolerance. However, how the developmental process is modified for such a drastic morphological change.

カテゴリー: 0.3.0.Leaf 葉, 3.11.Polypodiales, reduction 退化 | Reduction in leaf morphology 葉形態の退化 はコメントを受け付けていません。

Vessel element in angiosperms 被子植物の導管要素

アンボレラ目とスイレン目は道管要素を形成せず、仮導管のみを持つ(Carlquist 2012)。しかし、これらの目では、仮導管形態が道管形態に似ている部分もある。例えば、アンボレラは二次仮導管では穿孔板が貫通して道管要素のようになる傾向がある(Feild et al. 2000)。スイレン目では壁硬膜に大きな穴が開いている(Schneider and Carlquist 1995a, 1995b)。スイレン目に似た仮導管はショウブ目にも見られる(Carlquist and Schneider 1997)。仮導管と道管がどのような分子機構の違いによってできるのかがわかってくると、被子植物における水通導組織の起源と進化についてより明確な推測ができるようになるだろう。

Amborellales and Nymphaeales only have tracheids and do not have vessel elements as some angiosperms including Acorus and Winteraceae (Carlquist 2012). However, tracheids morphology partly becomes similar to vessel elements. For example, end walls of secondary tracheary elements of Amborella tend to be pitted in Amborella (Field et al. 2000). Pit membranes of Nymphalea have large pores (Schneider and Carlquist 1995a, 1995b). This tendency is also observed in Acorus (Carlquist and Schneider 1997). Understanding of the molecular mechanisms to from vessel and tracheary elements will give insight on the origin and evolution of water conducting tissues.

Carlquist, S. 2012. How wood evolves: A new synthesis. Botany 90: 901-940.

Carlquist, S. and Schneider, E.L. 1997. Origins and nature of vessles in monocotypledons. I. Acorus. Int. J. Plant Sci. 158: 51-56.

Feild, T.S., Zweiniecki, M.A., Brodribb, T., Jaffré, T., Donoghue, M.J., and Holbrook, N. M. 2000. Structure and function of tracheary elements in Amborella trichopoda. Internat. J. Plant Sci. 161: 705-712.

Schneider, E.L. and Carlquist, S. 1995a. Vessels in the roots of Barclaya roundifilia (Nymphaeaceae). Amer. J. Bot. 82: 1343-1349.

Schneider, E.L. and Carlquist, S. 1995b. Vessel origins in Nymphaeaceae: Euryale and Victoria. Bot. J. Linn. Soc. 119: 195-193.


カテゴリー: 0.2.0.Stem 茎, 5.01.Amborellales.アンボレラ目, 5.02.Nymphaeales.スイレン目 | Vessel element in angiosperms 被子植物の導管要素 はコメントを受け付けていません。

Anther inversion in Ericales ツツジ目の雄蕊の反転

ツツジ目のツツジ科、キリラ科、リョウブ科、マタタビ科、ロリデュラ科、サラセニア科では、葯が発生途中にひっくりかえり(Hermann and Palser 2000, Lofstrand et al. 2016)、これはこれらの群の共有派生形質と考えられる。

Ericaceae, Cyrillaceae, Clethraceae, Actinidiaceae, Roridulaceae, and Sarraceniaceae in the Ericales form stamens with anthers inverting during development (Hermann and Palser 2000, Lofstrand et al. 2016). This is a synapomorphic character of these families.

葯はツツジ科ネジキ属のVaccinium stamineumのように発生初期にひっくり返るものもあるし、リョウブ科リョウブのように開花時に反転するものもある。このような違いはツツジ科などでは、同じ科の属間でも見られる(Hermann and Palser 2000)。

Anthers of some taxa are inverted during the early stamen development as Vaccinium stamineum, while others are at the time of flower opening as Clethra barbinervis (Hermann and Palser 2000, Lofstrand et al. 2016). Such differences vary between genera in a family, such as the Ericaceae (Hermann and Palser 2000).


Stamens of Orthilia secunda in the Ericaceae invert at the flower opening.

Lofstrand, S.D., Von Balthazar, M., and Schonenberger, J. 2016. Early floral development and androecium organization in the sarracenioid clade (Actinidiaceae, Roridulaceae and Sarraceniaceae) of Ericales. Bot. J. Linn. Soc. 180: 295-318.

Hermann, P.M. and Palser, B.F. 2000. Stamen development in the Ericaceae. I. Anther wall, microsporogenesis, inversion, and appendages. 87: 934-957.

カテゴリー: 5.18.02.Ericales.ツツジ目, Deviated growth 偏差成長, organized morphogenesis and growth 調和した形態形成と成長, Stamen morphology 雄蕊形態, Twisting ねじれ | Anther inversion in Ericales ツツジ目の雄蕊の反転 はコメントを受け付けていません。

Phyllotaxis of Abelia grandiflora ハナゾノツクバネウツギの葉序


Abelia x grandiflora usually forms opposite leaves but long shoots form opposite, three-whorled, and four-whorled leaves.


Shoots formed at leaf axils of a last-year shoot form opposite leaves (arrows).


Shoots with four-whorled leaves originate from the base of previous shoots.

三輪性の葉を付けるシュートも株元から生える。対生の葉を付けるシュートは前年枝の葉腋だけでなく、株元から生えることもある。この場合、対生シュートの方が三輪性シュートよりも細い。花の場合、メリステムの直径が大きくなると花器官の数が多くなるので(Kitazawa and Fujimoto 2015)、この場合も、株の基部からでる徒長枝と葉腋からでる徒長枝でメリステムサイズが異なるために、対生、三輪性、四輪性の違いが生じているのかもしれない。多くの植物では分裂組織の大きさは一定している場合が多いし、葉序も一定しているのが普通である。どうしてハナゾノツクバネウツギだけこのような変化が起こるのだろうか。

Shoots with three-whorled leaves are formed at the base of previous shoots. Shoots with opposite leaves are sometimes formed at the base of previous shoots as well as leaf axes. When shoots with opposite leaves are formed at the base, the stem of opposite shoots is thinner than that of three whorled shoots. As the number of floral organ depends on the meristem size (Kitazawa and Fujimoto 2015), the difference of leaf number in a whole may be caused by the difference of meristem size.

Kitazawa, M.S. and Fujimoto, K. 2015. A dynamical phyllotaxis model to determine floral organ number. PLOS Compt. Biol. 11: e1004145.





カテゴリー:マツムシソウ目, Phyllotaxis 葉序 | Phyllotaxis of Abelia grandiflora ハナゾノツクバネウツギの葉序 はコメントを受け付けていません。

Cascabela キバナキョウチクトウ属


A style head and contacting petals prevent the own pollen entering. A part of filament merged with a petal functions as guides of probosces. A stigma where pollen from other individuals locates on the lower side of a style head.

キバナキョウチクソウのフォーチュンクッキーに似た乾果を使った中国の飾り物。赤い種子はマメ科のAdenanthera pavoninaの種子。

An ornament from China with dry fruits of Cascabela thevetia, Red seeds are Adenanthera pavonina in the Fabaceae.



カテゴリー: 0.5.0.Fruits,リンドウ目, Apocynaceae キョウチクトウ科, appendicula 付属体, Modification for pollination | タグ: | Cascabela キバナキョウチクトウ属 はコメントを受け付けていません。

Pollination of Trachelospermum asiaticum テイカカズラの受粉



Contorted corolla is also observed in Ixoroideae in the Rubiaceae.

Stamens and a gynoecium is connate and form a special morphology in Apocynoideae.

テイカカズラの受粉を観察した論文は見つからなかったので、同じ亜科のMandevilla tenuifoliaの研究(de Araujo et al. 2014)を参考に以下のように推定した。チョウなどの媒介昆虫の口吻は葯の間の隙間を通って花冠の奥の蜜にたどりつく。口吻を差し込むときは、媒介昆虫が花冠に乗っていないか乗ってすぐの状態なので、花冠と葯の隙間の間に隙間があり、口吻が柱頭に押しつけられることなく挿入される。しかし、口吻を抜くときには、昆虫の重みで花冠が傾き、口吻は葯の間の奥にある柱頭に押しつけられる。そうすると、口吻が抜かれるときに、まず花粉受容部で口吻に付いていた他の花の花粉がこしとられ、次に、粘着部で口吻に粘液が付き、そして、その粘液に二次提示された花粉が付き、別な花での受粉に使われる。

When proboscis is inserted, proboscis passes the slits formed between anther cones. At this moment, the pollinator insect is not landed or just landed on corolla and proboscis easily pass the slits without scraping pollen of other flowers on the proboscis. During the sacking of nectar, corolla is inclined and proboscis is pressed to the surface of gynoecium below the slit. When proboscis is retracted, other plant pollen stuck on the proboscis is scraped at the receptive part, then sticky fluid is stuck, and secondary presented pollen is trapped by the sticky fluid on the proboscis. This process is speculated by the study in Mandevilla (de Araujo et al. 2014).

de Araujo, L.D.A., Quirino, Z.G.M., and Machado, I.C. (2014). High specialisation in the pollination system of Mandevilla tenuifolia (JC Mikan) Woodson (Apocynaceae) drives the effectiveness of butterflies as pollinators. Plant Biol (Stuttg) 16, 947-955.

カテゴリー:リンドウ目, appendicula 付属体, Modification for pollination | Pollination of Trachelospermum asiaticum テイカカズラの受粉 はコメントを受け付けていません。

Accessory calyx of Lecanorchis ムヨウラン属の副萼


Lecanorchis has the accessory calyx. How and why is it formed?


カテゴリー: 5.06.07.Asparagales.キジカクシ目, 副萼 epicalyx | Accessory calyx of Lecanorchis ムヨウラン属の副萼 はコメントを受け付けていません。

Adventitious shoots of Polystichum craspedosorum ツルデンダの不定芽


As Polystichum craspedosorum, leaves of some ferns form shoot and root meristems at their tips. How is the leaf apical meristem reorganized into shoot and root meristems?

カテゴリー: 3.11.Polypodiales, Adventitious shoots 不定芽, 分裂場所制御 | Adventitious shoots of Polystichum craspedosorum ツルデンダの不定芽 はコメントを受け付けていません。

Zabelia イワツクバネウツギ属


A synapomorphic character of Zabelia is the petiole bases swollen to enclose axillary buds. How and why the bases are swollen?

カテゴリー: 0.2.Leaf base 葉柄の基部,マツムシソウ目, 副萼 epicalyx | Zabelia イワツクバネウツギ属 はコメントを受け付けていません。