ハンドロアンサス属がタベブイア属から独立した経緯とその特徴まで記されています。（訳責：前田久紀）。
Hodel, D.R., J.E. Henrich, K.J. Greby, and D. Yansura. 2017. Handroanthus × lewisii (Bignoniaceae), a new hybrid from cultivation. Phytoneuron 2017-46: 1–21. Published 18 July 2017. ISSN 2153 733X
HANDROANTHUS ×LEWISII (BIGNONIACEAE),
A NEW HYBRID FROM CULTIVATION
イペー ヘプタフィーラ（ピンク花）とウンベラータ（黄花）の
栽培による新しいハイブリッド
イペー ヘプタフィーラ（ピンク花）とウンベラータ（黄花）の
栽培による新しいハイブリッド
DONALD R. HODEL University of California Cooperative Extension 700 W. Main St. Alhambra, California 91801 drhodel@ucanr.edu
JAMES E. HENRICH Los Angeles County Arboretum and Botanic Garden 301 N. Baldwin Ave. Arcadia, California 91007 jim.henrich@arboretum.org
KENNETH J. GREBY ArborPro, Inc. 22605 La Palma Ave. Yorba Linda, California 92887 fastfeat@gmail.com
DANIEL YANSURA 330 Carmel Ave. Pacifica, California 94044 dyansura@gmail.com
ABSTRACT
Handroanthus ×lewisii, an unusually handsome hybrid of Handroanthus heptaphyllus and H. umbellatus (trumpet trees, Bignoniaceae), is now well established at the Los Angeles County Arboretum and Botanic Garden in Arcadia, California, near Los Angeles, where it was first developed, and at several other locations in Southern California. Because it is gaining in popularity and might soon be marketed to retail nurseries, we provide formal botanical and common names for this hybrid.
概要
ヘプタフィーラとウンベラータの美しいハイブリッドが、カリフォルニア州アルカディアのLos Angeles County ArboretumとBotanic Gardenで順調に生育しています。 南カリフォルニアの他の各地で人気が高まっており、すぐに小売苗床に販売される可能性があるため、このハイブリッドの正式な植物名および一般名を付ける予定です。
Handroanthus Mattos comprises arguably the showiest winter- and spring-flowering trees in Southern California. Established in 1970 (Mattos 1970), the genus includes about 30 species of trees from Mexico to Argentina (Grose & Olmstead 2007) that most authors (e.g., Gentry 1992) previously included in Tabebuia Gomes ex. DC. Indeed, Handroanthus was largely unaccepted until the publication of Grose and Olmstead in 2007. When Mattos (1970) segregated out Handroanthus, he noted that it differed from Tabebuia in its palmately compound leaves and eight to nine vules/locules per ovary (vs. simple leaves and three to four ovules/locules per ovary in Tabebuia). However, Gentry (1972, 1992) insisted that Tabebuia was a natural lineage and should not be divided, and he was loathe to accept Handroanthus, which he never did. Based on more recent molecular studies, Grose and Olmstead (2007) divided Tabebuia into three genera: (1) Handroanthus, comprising mostly yellow-flowered species with various degrees of hairs covering the leaves and calyx and extremely dense wood containing large quantities of lapachol; (2) Roseodendron Miranda, including just two species having spathaceous calyxes with a texture similar to that of the corolla; and (3) Tabebuia, restricted to species having white to red or rarely yellow flowers with stalked or sessile lepidote scales.
Handroanthus Mattosは、間違いなく南カリフォルニアで最も見栄えのする冬および春の開花木で構成されています。 １９７０年に設立され（Ｍａｔｔｏｓ １９７０）、この属には、メキシコからアルゼンチンまでの約３０種の木が含まれています（Ｇｒｏｓｅ＆Ｏｌｍｓｔｅａｄ ２００７）。 以前はＴａｂｅｂｕｉａ Ｇｏｍｅｓ ｅｘDCに含まれていました（例えばＧｅｎｔｒｙ １９９２）。 確かに、ハンドロアンサスは2007年にGrose and Olmsteadが出版されるまでほとんど受け入れられませんでした。
マトス（1970）がハンドロアンサスを分離したとき、彼は掌状複合葉と1子房あたり8～9個の小茎/小丘でタベブイアとは異なると主張しました。 タベブイアの場合、1個の葉に3〜4個の胚珠/卵丘があります。しかし、Gentry（1972年、1992年）は、タベブイアは自然な系統であり、分割すべきではないと主張し、彼はハンドロアンサスを受け入れることを嫌がって決して受け容れませんでした。 Grose and Olmstead（2007）は、より最近の分子研究に基づいて、タベブイアを3つの属に分けました。
（1）ハンドロアンサスは、葉と萼(前田註：花も入れた記述もある）とを覆う多種多様の毛を持つ黄色い花の種と高濃度のラパコールを含む非常に密度が高い木材で構成される。
（2）ロゼオデンドロン ミランダ。花冠と似た感触をもつ散開状の萼を有する二つの種を含む。
（3）タベブイア。白から赤またはまれに黄色い花で、鱗付きの茎を持つ種と持たない種に限定される。
雌木と 同じ樹種の木
第1図 ハンドロアンサスには、カリフォルニア南部で最も壮観な冬および春の開花木が含まれている。ここに、ハンドロアンサス ウンベラータ×ヘプタフィーラ（カリフォルニア州）の雌しべの親がある（©D.R. Hodel）。
The two most common species in Southern California are (1) the pink-flowered Handroanthus heptaphyllus (Vell.) Mattos [Tabebuia heptaphylla (Vell.) Toledo], heretofore known as H. impetiginosus (Mart. ex DC.) Mattos [T. impetiginosa (Mart. ex DC.) Standl.], a name misapplied to material in Southern California and perhaps elsewhere (Hodel et al. 2015) (Fig. 1) and (2) the yellow-flowered H. chrysotrichus (Mart. ex DC.) Mattos [T. chrysotricha (Mart. ex DC.) Standl.]. The Los Angeles County Arboretum and Botanic Garden in Arcadia is primarily responsible for introducing these two species to the southern California nursery trade and landscape, where they are popularly known as pink or yellow trumpet trees (respectively) or pink or yellow tabs, the latter word being an abbreviated derivation of their former genus name. Other species sometimes encountered and mostly confined to botanical gardens and arboreta include the yellow-flowered H. ochraceus (Cham.) Mattos [T. ochracea (Cham.) Standl.] and H. umbellatus (Sond.) Mattos [T. umbellata (Sond.) Sandwith]
(Fig. 2). Tabebuia still exists, though, and includes 67 species, one of which, the pink flowered T. heterophylla (DC.) Britton, is in the desert plant collection in Balboa Park in San Diego.
カリフォルニア南部で最も一般的な二つの種は、（1）ピンク色の花を咲かせルハンドロアンサスヘプタフィーラ（Vell。）Mattos [タベブイアヘプタフィーラ（Vell。）Toledo]で、これまではハンドロアンサスンペチギノーザ（Mart。ex DC）として知られていた（前田註：この二つは全くの別種）。カリフォルニア州南部および他の地域で材料に誤って適用された名称（Hodel et al。2015）（図1）および（2）黄色の花をつけるハンドロアンサスクリストリーチャ（Mart。ex DC）。 DC。）Mattos [タベブイアクリストリーチャ（Mart。ex DC）Standl。]アルカディアのロサンゼルス郡樹木園と植物園は、主にこれらの2つの種を南カリフォルニアの苗床貿易と景観に紹介する責任があります。それらはそれぞれピンクまたは黄色のトランペットの木、またはピンクまたは黄色のタブとして広く知られています。以前の属名の短縮された派生語であること。時々遭遇しそして大部分は植物園と樹木園に限られた他の種は黄色の花を咲かせたH. ochraceus（Cham。）Mattos [T. ochracea（Cham。）Standl。]およびH. umbellatus（Sond。）Mattos [T. umbellata（ソンド。）Sandwith]
（図2）。 タベブイアはまだ存在し、67種が含まれている。そのうちの1種、ピンクの花の咲くタベブイアヘテロフィーラ（DC）Brittonは、サンディエゴのバルボア公園の砂漠植物コレクションにある。
（図2）。 タベブイアはまだ存在し、67種が含まれている。そのうちの1種、ピンクの花の咲くタベブイアヘテロフィーラ（DC）Brittonは、サンディエゴのバルボア公園の砂漠植物コレクションにある。
The extremely variable but typically larger Handroanthus heptaphyllus can flower from November through April with a peak in February and March while the other species, mostly yellowflowered and generally of smaller habit flower mostly in February and March. Because they bloom in dense, large, many-flowered clusters at the ends of bare branches when most or all of the leaves have dropped, they are nothing short of spectacular and garner much well deserved attention when in full flower.
大きく変動はするが、典型的には大半のハンドロアンサスヘプタフィーラは11月から4月にかけて、2月と3月にピークを迎えますが、他の種は主に黄色の花を咲かせ、一般的に2月と3月に小さな習慣をします。 大部分または全部の葉が落ちたとき、それらは裸の枝の終わりに密で大きくて、多くの花が房状に咲いているので、それらは壮観そのもので、満開の時には注目に値する。
雄木と 同じ樹種の木
Hodel).
第2図 親であるハンドロアンサスウンベラータは、この属の黄色い花の種の1つである（Los Angeles County Arboretum and Botanic Garden、1967-1455-P * 3）（©D.R.Hodel）。
In 1970, the late George Lewis, a senior gardener at the Los Angeles County Arboretum and
Botanic Gardens, first made the hybrid (now popularly known as the apricot tab) between
Handroanthus heptaphyllus (he referred to it as Tabebuia impetiginosa) and, as it turns out, H.
umbellatus. However, the identity of one of the latter parent was not specified and has only recently
been resolved. Lewis’s records clearly show that H. impetiginosus (1955-2559-S, ex Porto Allegre,
Brazil) was the pistillate (seed) parent. Unfortunately, he did not specify the staminate (pollen)
parent; however, because H. chrysotrichus was by far the most common yellow-flowered taxon in the
Arboretum at the time, we initially assumed it was the staminate parent. At least four accessions from
1953 to 1966 totaling 24 plants of H. chrysotrichus, which possibly would have been sufficiently
mature to flower by 1970, were extant in the Arboretum as late as 2007. In contrast, one accession
from 1953, totaling two plants of H. ochraceus and three accessions from 1966 to 1968, totaling five
plants of H. umbellatus, which possibly would have been sufficiently mature to flower by 1970, were
extant in the Arboretum as late as 2007. The Arboretum featured and promoted H. chrysotrichus in
particular, formally introducing it to the nursery trade in April 1964. Another possibility is that the
staminate parent was not even at the Arboretum and Lewis had pollen sent to him from elsewhere.
Nonetheless, and despite this seemingly overwhelming evidence favoring Handroanthus
chrysotrichus as the staminate parent, we became suspicious of this parentage when comparing the
habit and leaf indumentum of the hybrid with its putative staminate parent. Coauthor Greby first
noted that the branching structure of the hybrid was much more similar to that of H. umbellatus than
that of H. chrysotrichus. The hybrid and H. umbellatus tend to have two to three strongly codominant
leaders while H. chrysotrichus has a more central leader. Also, the smaller, much less hairy leaflets of the hybrid are more similar to those of H. umbellatus. These suspicions prompted us to
look for a more definitive resolution of the staminate parent. We determined the staminate and
confirmed the pistillate parents of the hybrid by comparing DNA sequences (ITS2) of four candidate
parents with that of samples from two hybrid trees, one from the Arboretum’s original cross and one
from a landscape street tree of unknown origin in Whittier, California, about 40 km distant. At three
positions where the candidate parents differ from each other, the hybrids display a sequence trace
resulting from the combination of the two parents (H. heptaphyllus and H. umbellatus) (Figs. 3A and
B, 4A and B).
1970年に、ロサンゼルス郡樹木園および植物園の年長の庭師、故ジョージ・ルイスがハンドロアンサスヘプタフィーラ（彼はそれをタベブイアインペティギノーザと呼んだ）と、ハンドロアンサスウンベラータとの間にハイブリッドを最初に造りました。しかし、後者のアイデンティティは特定されておらず、ごく最近になって解決されました。ルイスの記録は明らかにハンドロアンサスインペティギノーザ（1955-2559-S、ex Porto Allegre、ブラジル）が雌しべ（種子）の親だったことを示しています。残念なことに、彼は花粉の親を明確にしていませんでした。しかし、当時はハンドロアンサスクリソツリーチャが樹木園で最も一般的な黄色い花の分類群であったため、当初はそれが雄花の親であると仮定しました。少なくとも1953年から1966年までに合計24本のハンドロアンサスクリソツリーチャが開花するまで十分に成熟していたましが、一方、ハンドロアンサスオクラセアを1953年から1本受入、これで合計2本のハンドロアンサスオクラセア、更には1966年から1968年までに3本を受入れましたのて合計5本、1970年までにおそらく十分に開花するまでに成熟していたであろうハンドロアンサスウンベラータは、最低でも2007年までは樹木園に存在しました。樹木園は特に1964年4月に特色があるハンドロアンサスクリソツリーチャを養育業に正式に紹介して、宣伝しました。もう一つの可能性は雄花の親が樹木園にさえなく、ルイスが他の場所から彼に送ってもらったということです。
それにもかかわらず、そしてハンドロアンサスクリソツリーチャを雄花親にふさわしいと思わせる一見圧倒的な証拠にもかかわらず、我々はこの親子関係を比較するとき疑わしくなりました。
その推定の親とそれを親とするハイブリッドの習性と葉の密毛。 Coauthor Grebyは、ハイブリッドの分岐構造はハンドロアンサスウンベラータの分岐構造はハンドロアンサスクリストリーチャのそれよりはるかに類似していることを最初に指摘した。ハイブリッドとハンドロアンサスウンベラータは2〜3個の強い共優性の分枝（前田註：多分枝のことと思われる）を持つ傾向がありますが、ハンドロアンサスクリストリーチャはより中心的なリーダーを持っています。また、ハイブリッドのより小さく、はるかに少ない毛状の小葉は、ハンドロアンサスウンベラータのものに、より類似しています。これらの疑いのため、私たちは雄花親のより明確な結論を追及しました。 4つの候補親のDNA配列（ITS2）を、二本のハイブリット樹からのサンプル（一つは樹木園の元の交配からのもの、および一つは未知の起源の景観ストリートツリーからのもの、カリフォルニア、約40 kmの距離）と比較することによって、混交子の雄花親を決定し、ハイブリットの両親を確認しました。候補親が互いに異なる3つの位置で、ハイブリッドは2つの親（H. heptaphyllusおよびH. umbellatus）の組み合わせから生じる配列トレースを示す（図3AおよびB、4AおよびB）。
hybrid Handroanthus x lewisii (Hxl-1) at the Los Angeles County Arboretum and Botanical Garden,
Arcadia, California. Handroanthus hepataphyllus was known to be one of the parents.
第3図 四つの親候補のDNA配列（5.8S-ITS2）と、ロサンゼルス郡樹木および植物園におけるハイブリッド、カリフォルニア州アルカディア。 ハンドロアンサスヘプタフィーラは両親の一人として知られていた。
A. Sequence traces of four parental candidates and the hybrid. Arrows point to three positions, which
show variations among the potential candidates. The hybrid Hxl-1 shows a combined trace for H.heptaphyllus and H. umbellatus. Hc, H. chrysotrichus; Hh, H. heptaphyllus; Ho, H. ochraceus; Hu,
H. umbellatus.
A. 四人の親の候補者と雑種のシーケンストレース。 矢印は三つの位置を指している。潜在的な候補者間の変動を示す。 ハイブリッドは、ヘプタフィーラとウンベラータの組み合わせのトレースを示している。 Hcはハンドロアンサスクリストリーチャ、Hhハハンドロアンサスヘプタフィーラ。 Hoはハンドロアンサスオクラセア、 Huはハンドロアンサスウンベラータ。
part A. The hybrid Hxl-1 shows a combined sequence for H. heptaphyllus and H. umbellatus. Hc, H.
chrysotrichus; Hh, H. heptaphyllus; Ho. H. ochraceus; Hu, H. umbellatus.
B． 微量のヌクレオチド配列へのトレースの転移。矢印は、パートAで識別された3つの位置を指す。
Hc、クリソツリーチャ。Hh、ヘプタフィーラ。 Ho、 オクラセア、 Hu、ウンベラータ。
Hc、クリソツリーチャ。Hh、ヘプタフィーラ。 Ho、 オクラセア、 Hu、ウンベラータ。
Figure 4. A comparison of DNA sequences (5.8S-ITS2) from four parental candidates to that of the
hybrid Handroanthus x lewisii (Hxl-2) at Whittier, California. Handroanthus hepataphyllus was
known to be one of the parents.
第4図 4種の親候補とカリフォルニア州WhittierのハイブリッドHandroanthus x lewisii（Hxl-2）のDNA配列（5.8S-ITS2）の比較。ハンドロアンスヘプタフィーラ は両親の一人として知られている。
A. Sequence traces of four parental candidates and the hybrid. Arrows point to three positions, which
show variations among the potential candidates. The hybrid Hxl-2 shows a combined trace for H.
heptaphyllus and H. umbellatus. Hc, H. chrysotrichus; Hh, H. heptaphyllus; Ho, H. ochraceus; Hu,
H. umbellatus.
A. 4人の親の候補者とハイブリッドのシーケンストレース。 矢印は三つの位置を指している。これは、候補者間の違いを示している。 ハイブリッドHxl-2はハンドロアンサスヘプタフィーラとハンドロアンサスウンベラータとの複合トレースを示す。 Hc、ハンドロアンサスクリソツリーチャ。Ｈｈ、ハンドロアンサスヘプタフィーラ。 Ho、ハンドロアンサスオクラセア。Hu、ハンドロアンサスウンベラータ。
part A. The hybrid Hxl-2 shows a combined sequence for H. heptaphyllus and H. umbellatus. Hc, H.
chrysotrichus; Hh, H. heptaphyllus; Ho. H. ochraceus; Hu, H. umbellatus.
B．痕跡のニュウクレオチド配列への転移。 矢印は、パートＡで同定された三つの位置を指す。ハイブリッドＨｘｌ － ２は、ハンドロアンサスヘプタフィーラとハンドロアンサスウンベラータの組み合わせ。 Ho、ハンドロアンサスオクラセア。Hc、ハンドロアンサスクリストリーチャ。Hh、ハンドロアンサスヘプタフィーラおよび Hu、ハンドロアンサスウンベラータ。
heptaphyllus (Vell.) Mattos × H. umbellatus (Sond.) Mattos]. TYPE: CULTIVATED. U.S.A. California. Los Angeles County: Arcadia, Los Angeles County Arboretum and Botanic Garden, 7 Mar 2015, 1970-0966-S*1, J. Henrich & D.R. Hodel 627 (holotype: LASCA).
This new hybrid shares characters of both parents. In habit and branching structure it is more
like Handroanthus umbellatus; in its glabrous or glabrescent leaves it is similar to both parents but the
toothed leaflet margins are similar to those of H. heptaphyllus; in flower it is more like H. umbellatus
initially with more yellow but aging to more like H. heptaphyllus with more pink or lavender, and in
its mealy pubescent calyx is more similar to that of H. heptaphyllus; in its mostly glabrous fruit it is
similar to both parents but lacks the strongly striate ridges of H. heptaphyllus. Table 1 and Figures 5
and 6 provide a comparison of characters of Handroanthus ×lewisii and its parents. Figures 5-18.
Tree, small to medium tree (Fig. 7), to ca. 15 m tall after 45 years but typically flowering when as small as 3-5 m tall. Trunk to ca. 30 cm DBH, typically with 2-3 strongly co-dominant leaders (Fig. 8); bark pebbly, grayish, tan in crevices between “pebbles” (Fig. 9); irregularly branched but typically scaffold branches regularly spaced and spreading horizontally to give “layered” look. Leaves palmately compound (Fig. 10), to ca. 23 × 19 cm, glossy green adaxially, paler abaxially, redbrown
when young; petiole ca. 10 cm long, ca. 1.5 mm diam.; leaflets 5(-7), 2 or 3 paired lateral and one terminal); terminal leaflet with petiolule ca. 4.5 cm long, ca. 0.9 mm diam., leaflet blade to 10.5 ×
4.5 cm, margins coarsely tooted in distal 4/5, 10 main lateral nerves on either side of midrib; distal
lateral leaflets with petiolule to ca. 3 cm long, ca. 0.8 mm diam., leaflet blade 9 × 3 cm, margins
coarsely toothed in distal 2/3; proximal lateral leaflets with petiolule to ca. 2 cm long, ca. 0.8 mm
diam., leaflet blade to 6 × 2 cm, margins coarsely toothed in distal 2/3 (Fig. 10); petiole and etiolules
grooved and +/- flattened adaxially, rounded abaxially, green, moderately to lightly covered with
short, tan to whitish tomentum, all leaflets broadly lanceolate to oblong-elliptic, apex acute to
acuminate, abruptly rounded, base cuneate, midrib abaxially with short, tan to whitish tomentum.
Inflorescence a terminal, compact, vertically compressed, up to 16-flowered raceme to ca. 20 cm
wide (Fig. 11). Flowers ( Figs. 14-15) bisexual, zygomorphic, densely placed along a short rachis,
paired or in threes, pedicels to 11 mm long, green, mealy pubescent. Calyx urn-shaped or
campanulate, with gland pits toward distal end, to ca. 12 × 9 mm, green proximally, lavender distally,
glabrous adaxially (inside), mealy pubescent with yellow-brown stellate hairs abaxially (outside),
slightly angled longitudinally, 5-lobed, lobes ca. 5 mm long, swollen (saccate) , rounded to acute.
Corolla ca. 8 × 6.5 cm, tubular or funnel-shaped, bi-laterally symmetrical (bilabiate), compressed to
create horizontally open (oval-shaped) throat; 5-lobed, lobes ca. 2 × 2.5 cm, membranous, pale
yellow, distal margin irregularly scalloped, erose, undulate; adaxially (inside) golden or dark yellow,
on ventral surface with conspicuous, depressed, reddish brown or burgundy nerves and long, straight
hairs, dorsal surface not so conspicuously nerved, abaxially (outside) with short, branched hairs on
ventral surface and golden with slight suffusion of magenta, dorsal surface with heavy suffusion of
magenta. Stamens 4, didynamous (2 long and 2 short), long to ca. 30 mm long, short to ca. 25 mm
long; filaments slender, ca. 8 mm diam. at base and there adnate to corolla and with glandular hairs,
ca. 0.5 mm diam. distally and glabrous; anthers ca. 7 mm long, divergent; staminode 1, to ca. 7 mm
long. Pistil ca. 45 mm long; ovary ca. 7 × 1.2 mm, green, glabrous; style to ca. 35 mm long, ca. 0.7
mm diam., very light green; stigma flattened, ca. 2 × 1.5 mm, very pale yellow, eventually bi-lobed.
Pistil with 5, laterally fused, quadrat nectary glands at base, these to ca. 2 × 1.5 mm. Fruits few (less
than 20 per tree), to ca. 50 × 1 cm, cylindrical, green, glabrous (Fig. 12); seeds ca. 10-15 × 5-10 mm,
thin, bialate, with hyaline-membranaceous wings clearly demarcated from the body, rarely fertile.
D. R. Hodel 627, holotype) and its two parents, H. umbellatus (left, 1967-1455-P*3) and H. heptaphyllus (right) at the Los Angeles County Arboretum and Botanic Garden (© D.R. Hodel).
第5図 ハイブリッド（中央、1970-0966-S * 1、J.Henrich＆amp; DR Hodel 627、ホロタイプ）とその2つの親、左：（ハンドロアンサスウンベラータ1967-1455-P *）の花序、右：ハンドロアンサスヘプタフィーラ（©DR Hodel）。ロサンゼルス郡樹木園植物園
第6図 中央、ハイブリッド（1970-0966-S * 1、J。Henrich＆amp; DR Hodel 627、ホロタイプ）とその２つの親である、左：ハンドロアンサスウンベラータ（1967-1455-P *）、右：ハンドロアンサスヘプタフィーラの花の比較。 ロサンゼルス郡樹木園植物園（©DR Hodel）。
第7図 ハイブリッドは通常、中小木である。（Los Angeles County Arboretum and Botanic Garden）（©D.R. Hodel）
Figure 8. Handroanthus ×lewisii typically has two to three codominant leaders (Los Angeles County
Arboretum and Botanic Garden) (© D.R. Hodel).
第8図 ハイブリッドは通常2〜3本の共優位の分枝を持っている。（Los Angeles County ArboretumとBotanic Garden）（©D.R. Hodel）。
Figure 9. The bark of Handroanthus ×lewisii is pebbly and grayish (Los Angeles County Arboretum and Botanic Garden) (© D.R. Hodel).
第9図 ハイブリッドの樹皮は小石状で灰色がかっている（Los Angeles County Arboretum and Botanic Garden）（©D.R. Hodel）。
Figure 10. Leaves of Handroanthus ×lewisii are palmately compound with five to seven leaflets with
coarsely toothed margins (© Los Angeles County Arboretum and Botanic Garden) (© D.R. Hodel).
第10図 ハイブリッドの葉は、5〜7枚の掌状で粗い鋸歯状の外縁で構成されている（©Los Angeles County Arboretum and Botanic Garden）（©D.R. Hodel）。
Figure 11. Inflorescence of Handroanthus ×lewisii are a terminal, compact, vertically compressed, up to 16-flowered raceme to 20 cm wide (Los Angeles County Arboretum and Botanic Garden) (© D.R. Hodel).
第11図 ハイブリッドの花序は、垂直方向に圧縮された幅20 cm、16個までの花のコンパクトな総状花序である。（Los Angeles County Arboretum and Botanic Garden）（©D.R. Hodel）
Figure 12. Fruits of Handroanthus ×lewisii are few, cylindrical, green, and glabrous (Los Angeles County Arboretum and Botanic Garden) (© D.R. Hodel).
第12図 ハイブリッドの果実は、極めて少なく、円筒形で、緑色で、そして無毛です（Los Angeles County Arboretum and Botanic Garden）（©D.R. Hodel）。
Additional specimens examined. CULTIVATED. USA. California. Los Angeles Co.:
Arcadia, Los Angeles County Arboretum and Botanic Garden, 1970-0966-S*2, Henrich & Hodel 628
(LASCA,), 1970-0966-S*3, 629 (LASCA); Whittier, 9923 Colima Rd. (33°56'49.349"N,
118°00'29.005"W) Henrich et al. 622 (LASCA), 10145 Colima Rd. (33°56'37.648"N,
118°00'37.919"W) Henrich et al. 621 (LASCA.)
Arcadia, Los Angeles County Arboretum and Botanic Garden, 1970-0966-S*2, Henrich & Hodel 628
(LASCA,), 1970-0966-S*3, 629 (LASCA); Whittier, 9923 Colima Rd. (33°56'49.349"N,
118°00'29.005"W) Henrich et al. 622 (LASCA), 10145 Colima Rd. (33°56'37.648"N,
118°00'37.919"W) Henrich et al. 621 (LASCA.)
DISCUSSION
The epithet honors the late George Lewis, who first made the hybrid cross and who had a 33-
year career with the Los Angeles County Arboretum and Botanic Garden, from 1957 to 1970, where
he rose to the rank of senior gardener, and then later at Descanso Gardens, La Cañada Flintridge, from 1970 to 1990, where he rose to the rank of superintendent. We designate the cultivar name ‘Apricot’
and the common name apricot tab because they refer to the general color of the flowers and were
originally coined by Arboretum staff.
The flower color of Handroanthus ×lewisii deserves a detailed discussion. When viewed
from a distance the flowers appear to be apricot-colored, a light yellowish orange (Fig. 13). However,
when viewed closely, individual colors contributed by each parent are clearly evident (Fig. 14). The
adaxial or inside surface of the corolla is golden yellow, the color darkest proximally and lightest
distally where the lobes are nearly membranous. The abaxial or outside surface of the corolla is
golden yellow with a light suffusion of magenta on the ventral side and a heavy suffusion on the
dorsal side. The suffusion of magenta on the dorsal side is heaviest or darkest proximally and lightest
distally.
All of these flower colors transition as they age; generally the flowers open more yellow,
more like Handroanthus umbellatus, and less magenta, less like H. heptaphyllus, then age to less
yellow and more magenta. The yellow fades adaxially nearly to white and abaxially to whitish or
ivory with irregular tinges of magenta. The yellow actually masks the magenta; fading away it leaves
or reveals the magenta base, intensifying the magenta. Once fallen on the ground, the magenta
intensifies even more. Also, one’s distance and angle from the tree, angle of the sun, and one’s
position relative to the sun tend to influence flower color.
Three trees from Lewis’s original 1970 cross are extant at the Los Angeles County Arboretum
and Botanic Garden. Located at the top of Tallac Knoll, the three are about 20 feet apart in a line and
are accessioned as 1970-0966-S*1 (Fig. 16), 1970-0966-S*2, and 1970-0966-S*3, respectively north
to south. Similar in habit, size, and flowers, they are about 15 m tall; have trunks 42.9 cm (25.9 +
17.0), 29.9 cm, and 24.3 cm DBH, respectively; and bloom in February and March. Also, at least
eight of the grafted apricot tabs are planted elsewhere at the Arboretum, and several more were
distributed through Arboretum plant sales and as gifts to other botanical gardens. Notable trees are at
the South Coast Botanic Garden in Palos Verdes Peninsula and on Colima Road south of Whittier
Blvd. in Whittier (Figs. 17-18), both in Los Angeles County; the home of plant enthusiast Brent
Wigand in Wildomar, Riverside County; and several other private gardens. Most of these grafted
plants are in the same or similar age/size class, are about 5 m tall and wide and have trunks 10 to 15
cm DBH.
Others have made this hybrid in recent years. Eric Schmidt (pers. com.) of Harry P. Leu
Gardens in Orlando, Florida notes that Bernie Peterson of Rockledge Gardens in Cocoa, Florida has
made several hybrids involving various combinations of Handroanthus chrysotrichus, H.
heptaphyllus, H. impetiginosus, and H. umbellatus. One of the hybrids made was perhaps H.
×lewisii.
Figure 13. When viewed from a distance the flowers of Handroanthus ×lewisii appear to be apricot
colored, a light yellowish orange (Los Angeles County Arboretum and Botanic Garden, 1970-0966-S*1, J. Henrich & D.R. Hodel 627, holotype) (© D.R. Hodel).
第13図 遠くから見ると、ハイブリッドの花はアンズ色で、淡いオレンジ色に見える（Los Angeles County Arboretum and Botanic Garden、1970-0966-S * 1、J. Henrich＆amp; DR Hodel 627、 ホロタイプ）（©DR Hodel）。
Figure 14. When viewed closely, individual colors contributed by each parent are clearly evident in
flowers of Handroanthus ×lewisii (Los Angeles County Arboretum and Botanic Garden, 1970-0966-S*1, J. Henrich & D.R. Hodel 627, holotype) (© D.R. Hodel).
第14図 精密に見たとき、各親によって与えられた個々の色は、ハイブリッドの花において明確である（Los Angeles County Arboretum and Botanic Garden、1970-0966-S * 1、J。Henrich＆amp; DR Hodel 627、Holotype）。 （©DR Hodel）。
Figure 15. Flowers of Handroanthus ×lewisii are bisexual, zygomorphic, densely placed along a short
rachis, and yellow with suffusion of magenta (Los Angeles County Arboretum and Botanic Garden) (©D.R. Hodel).
第15図 ハイブリッドの花は両性で、左右対称で、短い花軸に沿って密に配置され、黄色がかったマゼンタ色である。（Los Angeles County ArboretumとBotanic Garden）（©D.R。Hodel）
Figure 16. Marianne Hodel (foreground) and coauthor James E. Henrich provide scale for one of the three trees of Handroanthus ×lewisii from Lewis’s original 1970 cross (Los Angeles County Arboretum and Botanic Garden, 1970-0966-S*1, Henrich & Hodel 627, holotype) (© D.R. Hodel).
第16図 Marianne Hodel（前）と共著者のJames E. Henrich（後）が、ルイスの最初の1970年の交配によるハイブリッドの3本の木のうちの1本のスケールを提供します。（Los Angeles County Arboretum and Botanic Garden、1970-0966-S * 1、Henrich＆amp; amp） ; Hodel 627、holotype）（©DR Hodel）
Figure 17. The more northerly tree of Handroanthus ×lewisii at 9923 Colima Road in Whittier is likely from Lewis’s original 1970 cross (J. Henrich et al. 622) (© D.R. Hodel).
第17図 Whittierの9923 Colima Roadにあるハイブリッドのもっと北の木は、ルイスの最初の1970年の交配によるものである可能性がある（J. Henrich et al。622）（©D.R. Hodel）
CULTIVATION AND MANAGEMENT
The apricot tab does not readily produce fruits, which is advantageous for those managing this tree in the landscape. Managers have to contend with little fruit and seed litter and no seedlings appearing as weeds. In contrast, Handroanthus heptaphyllus and H. umbellatus, especially the former, produce abundant fruits that are rather unattractive when persisting on the tree and liberate great quantities of seeds, many of which germinate in the landscape and become weeds.
The apricot tab is readily propagated by grafting. Mary Foote, the Arboretum’s plant nursery
manager in the 1980s and early 1990s, successfully grafted it, using Handroanthus heptaphyllus as
the root stock. Scion wood was from one or more of the original three extant trees on Tallac Knoll
but which particular tree or trees were not always specified. Current nursery manager Sherry Tobin
used the cleft graft technique to propagate the Apricot Tab successfully on to seedling-grown H.
heptaphyllus. The apricot tab can also likely be propagated from semi-hardwood tip cuttings made
after flowering and prior to growth flushing; the use of rooting hormone, bottom heat, overhead mist,
and high light would probably yield the best results. Air layering is another possible method to
propagate the apricot tab. However, plants grafted on to seedlings might develop a deeper, well
structured root system that would provide better anchorage and support than cutting-grown or airlayered trees. This situation has occurred in Hawaii with the rainbow shower (Cassia × nealiae H.A.Irwin & Barneby), where grafting was recommended over air layering because of its stronger root system (Hickok 1954). Indeed, seedlings of H. heptaphyllus typically develop a rather deep, central taproot from which other roots then arise, and they are unusually difficult to pull out of the garden as weeds.
Figure 18. The more northerly tree of Handroanthus ×lewisii at 9923 Colima Road in Whittier has
exceedingly handsome flowers in their brightness, intensity, purity, and demarcation of the magenta and yellow colors (J. Henrich et al. 622) (© D.R. Hodel).
第18図 Whittierの9923 Colima Roadにあるハイブリッドより北方の木は、明るさ、彩度、純度、そしてマゼンタと黄色の色の境界において非常に魅力的な花を持っている（J. Henrich et al.622）（©DR Hodel ）
Little training and pruning are necessary to achieve a well structured apricot tab because it tends to grow upright with several strong leaders and layers of horizontal branches radially and vertically well spaced along the trunk. However, if necessary, prune and train to a central leader, subordinating lateral branches until the desired height is attained, and a handsome, well structured tree will result.
Pests, diseases, and nutritional disorders are unknown for the apricot tab in the landscape in
southern California. Providing proper cultivation, including planting, mulch, and judicious irrigation,
will preclude most problems. The most limiting factor in their cultivation might be cold, but the
apricot tab has tolerated temperatures to about -6 C for short periods at night with little or no damage
and has recovered with damage from even colder temperatures. Based on the distribution and
ecology of its parents and their performance in southern California, the apricot tab could probably be
classified as a low water user and, once well established in the landscape, would likely require deep
irrigation (to 30 cm deep) only one to two times a month in the summer and much less frequently at
other times, especially if there is sufficient rain. Indeed, the two trees in Whittier, in a paved-over
median with 75 cm cutouts, apparently receive little or no irrigation and at the end of nearly four
years of severe drought are still performing adequately if not outstandingly; thus, like many other
woody trees and shrubs, the apricot tab likely needs only about 30 to 40% of reference
evapotranspiration for the site (ETo) once well established.
ACKNOWLEDGEMENTS
We thank Mike Montoya, John Provine, Brent Wigand, Sherry Tobin, Susan Eubank, and
Joan DeFato for answering our many queries concerning the Apricot Tab. Michael H. Grayum,
curator at the Missouri Botanical Garden and esteemed student of Mesoamerican plants, generously
reviewed the manuscript.
LITERATURE CITED
Gentry, A.H. 1972. Handroanthus (Bignoniaceae): A critique. Taxon 21: 113-114.
Gentry, A.H. 1992. "Bignoniaceae: Part II (Tribe Tecomeae)." Flora Neotropica Monograph 25 (part
2): 1–150.
Grose, S.O. and R.G. Olmstead. 2007. Taxonomic revisions in the polyphyletic genus Tabebuia s.l.
(Bignoniaceae). Syst. Bot. 32: 660–670.
Hickok, P. 1954. Island Showers. Honolulu Star-Bulletin, 13 February.
Hodel, D.R., M. Ritter, J.E. Henrich, K.J. Greby, K. Musial, and D. Hannon. 2015. Handroanthus
heptaphyllus, the correct name for the pink trumpet tree in southern California. PalmArbor
2015-3: 1–4.
Mattos, J.R. 1970. Handroanthus, um novo gênero para os “ipês” do Brasil. Lowfgrenia 50: 1–4
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