Hibiscus hamabo, the hardy yellow hibiscus,[1] is a species of shrub in the genus Hibiscus that is native to the coastlines of China, Japan, and Korea.[2] It is characterized by yellow flower coloring as well as orbicular shaped leaves. In its native environment it is a perennial.[3]
Hibiscus hamabo is a small tree/shrub found naturally near the coastal sands of Japan and Korea. This plant grows near sea level which means it needs to be highly salt resistant.[4] The water near the coastal sands of Japan and Korea are high in concentrations of salt. H. hamabo was also introduced and cultivated in India and the Pacific Islands.[2] H. hamabo can effectively be cultivated in USDA zones 8-13. It is much better acclimated to the cold weather than Hibiscus tiliaceus which is one of the reasons for it possibly being grown in gardens. It can be grown in gardens that have well-drained soils, sufficient sun exposure, moderate drought exposure and is tolerant to different levels of salt.[5]
From the Malvaceae family, H. hamabo is a terrestrial exotic perennial plant native to coastal regions of Asia, including China, Korea, and Japan. It is primarily found in coastal sands near sea levels and can grow 1-5m tall.[3] It is adapted to precipitation zones that range from 8b-13a and can sustain 60-90F (16-32 C.) temperatures. It prefers warm, wet conditions and average, moist, well-drained, fertile soils.[6] However, it is more cold tolerant than other Hibiscus, like the Hibiscus rosa-siennis, and is drought tolerant once established. H. hamabo is a semi-mangrove species adaptive with strong salt tolerance and waterlogging stress.[7] Unfortunately, there is not enough information on the interaction of this plant with other species.
Hibiscus hamabo is unique to most hibiscus plants. It fertilizes mid to late spring, closer to the summertime, and blooms every year during the summer period. H. hamabo is a halophyte with strong salt resistance that grows well in habitats with NaCl concentrations ranging from 1.1 to 1.5%.[4] H. hamabo is currently considered one of the best afforestation species for amelioration of soil salinization in coastal areas of eastern China. So far, only a few studies have investigated the mechanism of salt tolerance in H. hamabo, and a few have tested the changes in physiological properties in response to different salinity levels.[8]
Hibiscus hamabo height ranges from 1 to 5 meters tall.[2] They’re deciduous large shrubs/small trees which grow upright. The bark is dark brown or dark gray with vertical fissures.[1]
Hibiscus hamabo foliage is green, obovate or ovate shaped, and typically 1 to 3 inches long. Each leaf has a smooth top and a dense hairy underside. These leaves have 5 to 7 basal veins. Petioles are a gray/green color and range from 0.5 to 1 inch long. Stipules are 1 cm long.[1][3] Foliage is generally thick and soft to the touch.[5]
Flowers are 3 to 6 inches wide. They range from yellow to soft orange in color and fade out from an orange or dark red core. Flowers are usually found alone but can also be found in cymes or in axillary clusters. They begin to bloom in late spring and stay till mid-fall. These flowers produce a mild fragrance.[1] H. hamabo participates in sexual reproduction. The center of the flower is where the reproductive organs are located. H. hamabo has both male and female reproductive organs. The stamen, the male reproductive organ, is dark brown or dark red in color and the anthers are yellow. The pistil, the female reproductive organ is a dark brown/ dark red in color and longer than the stamen.[2][9] The fruit is a brown or copper-colored capsule 2.5 to 3.5 centimeters long and covered in brown hair.[3]
Flowering typically starts in July and lasts until August.[9] Similar to other Hibiscus, pollinators of this species include birds and insects such as bees, moths, and butterflies.[3] Self-pollination is also possible, with fruit and seed production and quality being higher than some other Hibiscus species that are self-pollinated. However, inbreeding depression can occur in populations where self-pollination is frequent.[9]
The fruit is commonly preyed upon by insects such as moth larvae, which bore into the fruit. Rehimena surusalis is a known predator of various hibiscus species, including H. hamabo.[9]
Hibiscus hamabo, the hardy yellow hibiscus, is a species of shrub in the genus Hibiscus that is native to the coastlines of China, Japan, and Korea. It is characterized by yellow flower coloring as well as orbicular shaped leaves. In its native environment it is a perennial.
Hibiscus hamabo là một loài thực vật có hoa trong họ Cẩm quỳ. Loài này được Siebold & Zucc. mô tả khoa học đầu tiên năm 1841.[1]
Bài viết liên quan đến phân họ Cẩm quỳ này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Hibiscus hamabo là một loài thực vật có hoa trong họ Cẩm quỳ. Loài này được Siebold & Zucc. mô tả khoa học đầu tiên năm 1841.
ハマボウ（浜朴あるいは黄槿）、学名 Hibiscus hamabo は、アオイ科の落葉低木。西日本から韓国済州島、奄美大島まで分布し、内湾海岸に自生する塩生植物である。夏に黄色の花を咲かせる。方言呼称にはヒシテバナ（鹿児島市喜入）等がある[1][2][3]。
樹高は1-5mほどの低木だが、枝はよく分かれ、株の内側はうっそうと茂る。周囲に障害がない所ではしばしば横に広がり、直径5mほどになる。葉は枝に互生する。直径3-8cmほどの円に近いハート形で、やや厚く、縁に細かい鋸歯がある。葉の裏や細い枝には灰白色の細毛が密生する。幹は灰色で多数の皮目がある。根は深くないが、倒れてもすぐ発根する[2][3]。
花期は7-8月で、直径7cm程度の、中心が赤褐色の黄色い花を咲かせる。花の形態は同属のハイビスカス、ムクゲ、フヨウ等に似る。５枚の花弁は付け根から回旋して伸び、中心の赤褐色部は船のスクリューのように見える。花は1日でしぼむが、大きな株は夏季に毎日次々と開花する[1][3]。秋には先端が尖った鶏卵形の実をつけ、中には長さ4-5mmの豆のような黒褐色の種子が十数個ほどできる。
種子は海水に浸っても死なずに浮遊し、海を通して分布を広げることができる[2][3]。秋-初冬には紅葉し、葉が赤や黄色に変色して落ちるが、実は翌春まで残ることも多い。
和名は「浜辺に生えるホオノキ」の意にとられ、漢字も「浜朴」と書くが、牧野富太郎は「ホウ」の意味を不明とし、「フヨウ」の転訛ではないかとしている。牧野はまた、もう一つの漢字名「黄槿」（黄色のムクゲ）も誤用であろうとしている[1]。
分布域は、太平洋側では千葉県以西、日本海側では韓国済州島-長崎県対馬-島根県隠岐諸島以南、南限は奄美大島である。日本海側の北限は嘗て長崎県対馬市佐護、次いで山口県萩市笠山とされてきたが、隠岐諸島の生息地発見で大きく更新された。群落が多いのは九州西部（長崎県-熊本県）および紀伊半島（和歌山県-三重県）のリアス式海岸の入り江だが、他にも大群落が見られる河口や入り江は多い[2][3][4]。
河口や内湾など、汽水域の潮間帯上部-潮上帯に根を下ろす。塩分に強く、満潮時には根元が海水に浸る位置に生えるが、海水が届かない位置にも生える。ヨシ、シオクグ、ハマサジ、メヒルギ等、他の塩生植物とも混生する。人為的なものを除けば海岸から離れて生えることはほぼない。また荒波が打ち寄せる海岸にも見られない。マングローブが発達しない九州以北ではハマジンチョウ、ハマナツメなどと並び特徴的な生態を示す木であり、「半マングローブ植物」とも呼ばれる[2]。
木材はキクラゲ原木栽培のホダ木に使われる。嘗ては木材を水中メガネの枠に、皮の繊維をロープに利用した[3]。園芸用に栽培されることもある。
現存する個体数は多く、栽培も行われているが、河川改修や海浜部造成のため、良好な群落は減少している。日本の環境省が作成した維管束植物レッドリストでは2012年版に至るまで掲載されていないが、絶滅種、または絶滅危惧種に指定している府県は2014年現在で1府19県に達し、本種の動向が注目されている。このうち大阪府では絶滅したとされている他、嘗て日本海側の北限とされていた長崎県対馬市佐護の群落も河川改修で消滅した[5][6][7]。
各自治体の条例により、天然記念物、または許可なき採集等を禁じた「希少野生動植物種」として指定される例もある[5]。
シンボルとして指定する市町村もある[5]。
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