Botanical Studies (2009) 50: 241-250.

*

Corresponding author: E-mail: bopeng@sinica.edu.tw.

INTRODUCTION

A total of 12 species of Begonia were recognized

by Chen (1993) in the Flora of Taiwan, 2

nd

edition,

with one natural hybrid, B. ¡Ñbuimontana Yamamoto,

recognized from southern Taiwan (Peng and Chen, 1991).

Subsequently, a second natural hybrid, B. ¡Ñtaipeiensis C.-I

Peng, was recognized from northern Taiwan (Peng and

Sue, 2000; Peng and Chiang, 2000) and five additional

species ¡XB. bouffordii C.-I Peng, B. chuyunshanensis

C.-I Peng & Y. K. Chen, B. pinglinensis C.-I Peng, B.

tengchiana C.-I Peng & Y. K. Chen, and B. wutaiana C.-I

Peng & Y. K. Chen¡Xwere described (Peng et al., 2005).

In continuation of our systematic studies of Asian Begonia

(Fang et al., 2006; Ku et al., 2006; Peng et al., 2006a;

Peng et al., 2006b; Gu et al., 2007; Liu et al., 2007; Peng

et al., 2007; Ku et al., 2008; Peng et al., 2008a; Peng et

al., 2008b), we document here a third natural hybrid, B. ¡Ñ

chungii, from central Taiwan.

MATERIALS AND METHODS

Materials

Specimens of Begonia ¡Ñchungii, B. longifolia and

B. palmata were collected from wild populations

and cultivated in the experimental greenhouse for

morphological comparison, SEM studies, and cytological

examination. Vouchers are deposited at HAST.

Chromosome preparations

Meiosis was observed in flower buds fixed in a 3:1

mixture of 95% ethanol and glacial acetic acid and

Begonia ¡Ñchungii (Begoniaceae), a new natural hybrid in

Taiwan

Ching-I PENG* and Shin-Ming KU

Herbarium (HAST), Biodiversity Research Center, Academia Sinica, Nangang, Taipei 115, Taiwan

(Received September 25, 2008; Accepted March 4, 2009)

ABSTRACT.

A new natural hybrid, Begonia ¡Ñchungii C.-I Peng & S. M. Ku, from central Taiwan, is

described and illustrated. Based on its morphology, geographical distribution, pollen stainability, seed set, and

cytology, and on experimental hybrids, we conclude that B. ¡Ñchungii is a natural hybrid between B. palmata D.

Don [sect. Platycentrum (Klotzsch) A. DC.] and B. longifolia Blume [sect. Sphenanthera (Hassk.) Warb.].

Key words: Begonia; Begonia ¡Ñchungii; Begonia longifolia; Begonia palmata;

Hybrids; Meiosis; Natural

hybridization; Taiwan; Taxonomy.

subsequently refrigerated. Prior to staining, the buds

were hydrolyzed for 10 minutes at 60¢XC in a 1:1 mixture

of concentrated HCl and 95% ethanol. They were then

squashed in FLP orcein (Jackson, 1973).

Cryo scanning electron microscopy

Fresh leaves of Begonia ¡Ñchungii, B. longifolia and

B. palmata were dissected and mounted on stubs. The

samples were frozen with liquid nitrogen slush, and then

transferred to a sample preparation chamber at -160¢XC.

After 5 min, when the temperature had risen to -130¢X

C, the samples were fractured and then etched for 10

min at -85¢XC. After coating at -130¢XC, the samples were

transferred to the SEM chamber and observed at -160¢XC

with a cryo scanning electron microscope (FEI Quanta 200

SEM/Quorum Cryo System PP2000TR FEI).

NEW SPECIES

Begonia ¡Ñchungii

C.-I Peng & S. M. Ku, hybr. nov.¡X

TYPE: TAIWAN. Nantou County, Luku Township,

Sitou, National Taiwan University Experimental

Forest. Cryptomeria plantation by the Tahsuehchih

("University Pond"), 120¢X46¡¦57" E, 23¢X44¡¦23" N,

elev. ca. 1,200 m, 8 Mar 1994, Ching-I Peng 17962

(holotype: HAST, here designated; isotypes: A, E, MO,

TAIF, TNM). Áé¤ó¬î®ü´Å Figures 1, 2

Herba perennis. Caulis erectus, 50-80 cm altus. Folia

obliqua, ovata usque anguste ovata, 11-24 cm longa, 5-15

cm lata. Flores masculi: tepala 4; stamina 60-80. Flores

foeminei: tepala 5(-6), subaequalia; ovarium triloculare,

inaequaliter 3-alatum; placenta axialis; styli 3. Grana pol-

linis fere in toto abortiva. Ovarium abortivum. Chromoso-

matum numerus: 2n = 22. Hybrida naturalis e B. longfolia

Blume et B. palmata D. Don genita.

SySTEMATICS

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Botanical Studies, Vol. 50, 2009

Figu re 1. Begonia ¡Ñchungii C.-I Peng & S. M. Ku. A, Flowering branch, A¡¦, Rhizome and base of stems; B, Portion of leaf,

adaxial surface, B¡¦, abaxial surface; C, Portion of petiole; D, Stipule; E, Bract; F, Staminate flower, face view, F¡¦, back view; G.,

Androecium, longit udinal section, showing filaments fused to a short cent ral column; H, Stamen, dorsal view, H¡¦, ventral view,

H¡¦¡¦, side view; I, Pistillate flower; J, J¡¦, Styles and stigmas; K, Cross section of ovary; L, Fruit. (All from Peng 17962, HAST).

PENG and KU ¡X

Begonia

¡Ñ

chungii

in Taiwan

243

Figure 2. Begonia ¡Ñchungii C.-I Peng & S. M. Ku. A, Habit; B, Stipule; C, Leaf; D, E, Portion of leaf, adaxial suface; F, Portion

of leaf, abaxial suface; G, Petiole; H, Stem bases and rhizome; I, Bracts; J, Inflorescence; K, Pistillate flower; L, Styles and

stigmas; M, Staminate flower; N, Androecium, longit udinal section; O, Fruit; P, Ovary, cross section. (All from P en g 17962,

HAST).

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Botanical Studies, Vol. 50, 2009

Erect, perennial, succulent herb with poorly developed

rhizomes. Stems ¡Ó zigzag, pilosulose at first, later

glabrescent, 50-80 cm high, to 4-9 mm thick, internodes

7-26 cm long. Stipules glabrous, caducous, triangular-

lanceolate, 10-20 mm long, 5-7 mm wide, apex acuminate,

margin entire. Leaves adaxially sparsely pilosulose or

scaberulous, abaxially sparingly pilosulose on major veins,

oblique, ovate to narrowly ovate,

11-24 cm long, 5-15 cm

wide, apex acuminate to caudate, base obliquely cordate,

margins serrate, shallowly lobed and irregularly serrulate

or denticulate; venation palmate-pinnate, basal veins 6-7;

petioles pilosulose or puberulent, later glabrescent,

10-23

cm long, to 4-7 mm across. Bracts glabrous or near so,

caducous, narrowly ovate to narrowly triangular, 5-20

mm long, 2-8 mm wide, apex acuminate, margin ciliate.

Inflorescence 4-9 cm long, axillary; peduncles ascending,

subglabrous or sparsely pilosulose, 3-8 cm long, 2-3.5

mm thick. Tepals white. Staminate flowers: pedicel ca.

2.5 cm, tepals 4, decussate, outer two broadly obovate

Table 1. Comparison of Begonia ¡Ñchungii with putative parents, B. longifolia and B. palmata.

Begonia palmata (Figure 7) Begonia ¡Ñchungii (Figures 1, 2) Begonia longifolia (Figure 8)

Rhizome

Creeping and elongated

Poorly developed

Poorly developed or lacking

Stem

35-90 cm

50-80 cm

45-110 cm

Indumentum

Rusty-lanate to tomentose Pilosulose

Glabrous

Leaf blade

Shape

Broadly ovate to orbicular,

palmately lobed

Narrowly ovate, serrate, shallowly

lobed

Broadly lanceolate to narrowly

ovate, almost entire

Indumentum

Adaxially hispidulose-

tomentulose; abaxially rusty-

lanate to tomentose

Adaxially sparingly pilosulose or

scaberulous; abaxially sparingly

pilosulose on major veins

Glabrous

Thickness (£gm )

130-150

160-180

180-200

Palisade cell size (£gm) 15-20(-30) ¡Ñ 12-18

30-35 ¡Ñ 17-23

35-45 ¡Ñ 25-30

Palisade tissue

1-2-layered

2-layered

3-layered

Veinlet on abaxial surface Raised

Nearly flat

Flat

Stomata complex on

abaxial surface

Normal; sometimes

heteromorphic

Frequently deformed

Normal; homomorphic

Bract

Abaxially tomentose, margin

ciliate

Abaxially glabrous, margin ciliate Abaxially glabrous, margin

eciliate

Peduncle (cm)

6-24

3-8

0.3-2

Androecium

Shape

Ovoid

Ovoid

Cup- or bowl-shaped

Androphore

Present

Absence

Absence

Anthers

Narrowly obovoid

Narrowly oblong-obovoid

Clavate

Pollen

Fertile; 16-23 ¡Ñ 9-13 £gm

Sterile, often deformed; 11-23 ¡Ñ

7-8 £gm

Fertile; 11-15 ¡Ñ 5-10 £gm

Styles

2

Usually 3

3

Ovary

2-locular, 3-winged

Usually 3-locular, 3-winged 3-locular, wingless

Fruits

Capsule

Capsule

Berry-like

Seeds

Viable

Abortive

Viable

Figure 3. Dist ribution and altitudinal maps of Begonia longi-

folia (¡³), B. palmata (¡µ) and B. ¡Ñchungii (¡¹) in Taiwan.

PENG and KU ¡X

Begonia

¡Ñ

chungii

in Taiwan

245

to orbicular, 15-25 mm long, 10-18 mm wide, inner two

oblanceolate to narrowly obovate, 7-20 mm long, 5-8

mm wide; androecium actinomorphic, ovoid, without

androphore, stamens ca. 60-80, golf-club shaped, anthers

narrowly obovoid to oblong, yellow,

2-3 mm long, 0.9-1.1

mm across, connective apex protruding, filaments 1.6-2.7

mm long (upper stamems longer), fused to a short central

column

.

Pollen grains irregular, shriveled and unstainable.

Carpellate flowers: pedicel 1.3-2 cm long, tepals 5(-6),

unequal to subequal, obovate, to oblong, the largest 15-21

mm long,

13-17 mm wide, the smallest 9-15 mm long,

6-9 mm wide;

styles 3, yellow, 4.9-5.3 mm long, at their

base fused ca. 0.5 mm long, each bifid; ovary nodding

or somewhat pendent, trigonous-ellipsoid, 3-locular,

longitudinally shallowly grooved between the locules, 3-

Figure 4. Meiotic chromosomes of Begonia ¡Ñchungii. A, 2II+ 18I; B, 4II + 14I; C, 7II + 8I; D, 8II + 6I (All from P e ng 15911,

HAST).

Figure 5. Microphotographs of pollen of Begonia. A, B. ¡Ñ

chungii (sterile pollen); B, B. plamata (fertile pollen); C, B.

longifolia (fertile pollen).

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Botanical Studies, Vol. 50, 2009

Figure 6. SEM microphotographs of Begonian palmata (A-E), B. ¡Ñchungii (F-J ), and B. longifolia (K-O). A, F, K, Indumentum

on petiole; B, G, L, Leaf adaxial surface; C, H, M, Cross section of leaf; D, I, N, Leaf abaxial surface; E, J, O, Stomata on

abaxial leaf surface, showing heteromorphic stomatal complex (E), deformed stomatal complex (J, arrows) and homomorphic

stomatal complex (O). (A-E from Peng 15985; F-J from Peng 17962; K-O from Peng 16792)

PENG and KU ¡X

Begonia

¡Ñ

chungii

in Taiwan

247

Fig ure 7. Begonia palmata D. Don. A, Habit; B, Habit, sterile plant with exposed creeping rhizomes; C, Stipule from erect stem

(left), from rhizome (right); D, Portion of leaf, adaxial suface; E, Developing inflorescence, showing trichomes; F, Inflorescence

(pink morph); G, Staminate flower (pinkish morph); H, Staminate flower (white morph); I, Pistillate flower (white morph), side

view; J, Pistillate fl ower (pinkish morph), face view; K, Cross s ection of a young capsule; L, Capsules; M, N, Dry, dehiscent

capsule.

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Botanical Studies, Vol. 50, 2009

Figure 8. Begonia longifolia Blume. A, B, Habit; C, Leaf, adaxial surface; D, Leaf, abaxial surface; E , Stipules; F, Stem base

with roots; G, H, Inflorescences; I, J, Staminate flowers, showing bowl-shaped androecium; K, Pistillate flower; L , Three stig-

matic bands in a pistillate flower; M, Berry-like fruit; N, Cross section of fruit; O, Berry-like fruits.

PENG and KU ¡X

Begonia

¡Ñ

chungii

in Taiwan

249

winged; placentae axile, bilamellate. Somatic chromosome

number, 2n = 22.

Additional specimens examined. TAIWAN. Nantou

County, Luku Township, Hsitou, National Taiwan

University Experimental Forest. Grassy floor of

Cryptomeria plantation by "Vacation Lodge", 120¢X47¡¦

34" E, 23¢X40¡¦04" N, elev. ca. 1,200 m, 17 Feb 1994, Peng

15911 (HAST).

Etymology. The specific epithet commemorates Dr.

Nien-June Chung (Áé¦~¶v), a keen botanist who has

accompanied the first author on many field trips and

who discovered and called our attention to this unusual

Begonia.

Notes. Based on morphological comparisons (Table

1), distribution (Figure 3), chromosome cytology (Figure

4), pollen stainability (Figure 5), and comparisons with

experimental hybrids, we concluded that the unusual plants

from Nantou County are F

1

hybrids between B. longifolia

[sect. Sphenanthera] and B. plamata [sect. Platycentrum].

The indumentum of the hybrid is intermediate between

those of its parents (Figure 6A-B, F-G, K-L). Figure 6C,

H, and M compare leaf thickness, palisade cell size, and

number of palisade cell layers in the three entities, again

showing an intermediate condition in B. ¡Ñchungii. Begonia

palmata has heteromorphic stomatal complexes, one kind

normal and the other with subsidiary cells of different

sizes and numbers (Figure 6E); B. longifolia has uniform,

normal stomatal complexes (Figure 6O); and the hybrid

B . ¡Ñ chungii has both normal and deformed stomatal

complexes (Figure 6J). In B. ¡Ñchungii, the deformed

stomatal complexes lack stomata.

Both putative parents, B. longifolia and B. palmata,

have 2n = 22 (Oginuma and Peng, 2002). Begonia ¡Ñ

chungii has the same chromosome number as its parents,

but exhibits irregular and inconsistent chromosome paring

in meiosis, ranging from 2 II + 18 I to 8 II+ 6 I (Figure 4).

Unlike the other two natural hybrids of Begonia

previously documented in Taiwan (B. ¡Ñbuimontana: Peng

and Chen, 1991; B. ¡Ñtaipeiensis: Peng and Sue, 2000), the

staminate flowers of B. ¡Ñchungii are not shed prematurely.

Begonia ¡Ñchungii produces capsules, but the seeds are

abortive.

Begonia ¡Ñ chungii probably consists of F

1

hybrids

only. Local populations are uniform morphologically,

and experimental F

1

hybrids are exactly similar to them.

Although the hybrids are sterile, the ease of vegetative

reproduction by fragments of stem or leaves allows them

to spread and persist. The periodic clearing of undergrowth

on slopes in the experimental forest may create conditions

favorable for their vegetative reproduction. Begonia ¡Ñ

chungii occurs only as scattered clumps at the type locality,

where it grows intermixed with its parents. It doubtless

occurs elsewhere where the ranges of the parental species

overlap.

Acknowledgments. We thank Peter H. Raven (MO) for

improving the manuscript; Qiner Yang (IBSC) for the

Latin diagnosis; Yi-Hsiu Lai for the chromosome spread;

Ming-Chao Yu for the line drawings; Kuo-Fang Chung

and Chih-Kai Yang for some of the photographs in Figures

7 and 8; Nien-June Chung, Hsiu-Lan Ho and Chih-Hsiung

Chen for assistance in the field. This study was supported

in part by grants from National Science Council (NSC95-

2621-B-001-007-MY3) and Academia Sinica, Taiwan to

CIP.

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