Short Communication |
Corresponding author: Vinita Gowda ( gowdav@iiserb.ac.in ) Academic editor: Yasen Mutafchiev
© 2018 Ajith Ashokan, Vinita Gowda.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Ashokan A, Gowda V (2018) Describing terminologies and discussing records: More discoveries of facultative vivipary in the genus Hedychium J.Koenig (Zingiberaceae) from Northeast India. PhytoKeys 96: 21-34. https://doi.org/10.3897/phytokeys.96.23461
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The authors introduce the term facultative vivipary for the first time in gingers and elaborate on this reproductive strategy. Four new observations of facultative vivipary are reported in the genus Hedychium which were discovered during botanical explorations by the authors in Northeast India (NE India) over the past three years. The viviparous taxa are H. marginatum C.B.Clarke, H. speciosum var. gardnerianum (Ker Gawl.) Sanoj & M.Sabu (previously, H. gardnerianum Sheppard ex Ker Gawl.), H. thyrsiforme Buch.-Ham. ex Sm. and H. urophyllum G.Lodd. The authors also attempt to summarise the occurrence of vivipary in the family Zingiberaceae from published reports and to clarify a taxonomic misidentification in a previously known report of vivipary in Hedychium elatum.
Facultative vivipary, gingers, Meghalaya, Nagaland, phenology, pseudovivipary, recalcitrant seeds
Vivipary in plants is a heterogeneous term that describes a unique and rare reproductive strategy where seedlings are precociously produced while still on the maternal parent (
True vivipary refers to vivipary sensu stricto and it is defined as penetration of a sexually reproduced embryo through the fruit pericarp and the resultant dispersal of this seedling (
Within the family Zingiberaceae, vivipary is rarely discussed as an important reproductive strategy, except in Hedychium elatum R.Br. by
Summary of published and personal records where vivipary sensu lato were identified within Zingiberaceae. All Globba synonyms following
Vivipary recorded in Zingiberaceae | Type of vivipary | Reference(s) |
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Alpinia Roxb. | ||
A. mutica Roxb. | Vivipary* |
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A. purpurata (Vieill.) K.Schum. | Pseudovivipary |
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Boesenbergia Kuntze | ||
B. parvula (Wall. ex Baker) Kuntze | Pseudovivipary |
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B. pulcherrima (Wall.) Kuntze | Pseudovivipary |
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Camptandra Ridl. | ||
C. latifolia Ridl. | Vivipary* |
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Curcuma L. | ||
C. coriacea Mangaly & M.Sabu | Vivipary* |
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Globba L. | ||
G. aurantiaca Miq. | Pseudovivipary |
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G. bicolor Gagnep. | Pseudovivipary |
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G. bulbifera Roxb. | Pseudovivipary |
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G. cambodgensis Gagnep. | Pseudovivipary |
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G. cernua Baker Synonym: G. brachycarpa Baker or G. trachycarpa Baker | Pseudovivipary |
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G. chinensis K.Schum. | Pseudovivipary |
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G. colpicola K.Schum. | Pseudovivipary |
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G. lancangensis Y.Y.Qian | Pseudovivipary |
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G. leucantha Miq. Synonym: G. pallidiflora Baker ex Ridl. | Pseudovivipary |
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G. marantina L. Synonyms: G. barthei Gagnep., G. ectobolos K.Schum., G. heterobractea K.Schum., G. strobilifera Zoll. & Moritzi | Pseudovivipary |
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G. multiflora Wall. Synonym: G. rubromaculata J.Lal & D.M.Verma | Pseudovivipary |
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G. parva Gagnep. | Pseudovivipary |
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G. pendula Roxb. Synonyms: G. calophylla Ridl., G. kingii Baker, G. panicoides Miq., G. stenothyrsa Baker, G. wallichii Baker | Pseudovivipary |
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G. platystachya Baker | Pseudovivipary |
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G. racemosa Sm. Synonyms: G. clarkei Baker, G. hookeri C.B.Clarke ex Baker | Pseudovivipary |
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G. ranongensis Picheans. & Tiyawora. | Pseudovivipary |
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G. schomburgkii Hook.f. Synonym: G. globulifera Gagnep. | Pseudovivipary |
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G. sessiliflora Sims Synonyms: G. canarensis Baker, G. careyana Roxb., G. ophioglossa Wight | Pseudovivipary |
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G. substrigosa Synonym: G. aphanantha K.Larsen | Pseudovivipary |
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G. unifolia Ridl. | Pseudovivipary |
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G. ustulata Gagnep. | Pseudovivipary |
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Hedychium J.Koenig | ||
H. greenii W.W.Sm. | Pseudovivipary |
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H. marginatum C.B.Clarke | Facultative vivipary | This paper |
H. speciosum var. gardnerianum (Ker Gawl.) Sanoj & M.Sabu Synonym: H. gardnerianum Sheppard ex Ker Gawl. | Facultative vivipary |
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H. thyrsiforme Buch.-Ham. ex Sm. | Facultative vivipary | This paper |
H. urophyllum G.Lodd. | Facultative vivipary | This paper |
Hornstedtia Retz. | ||
H. scyphifera J.Koenig ex Steud. | Vivipary* | Leong-Škorničková (pers. comm.) |
Larsenianthus W.J.Kress & Mood | ||
L. careyanus (Benth. & Hook.f.) W.J.Kress & Mood | Pseudovivipary |
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Zingiber Mill. | ||
Z. puberulum Ridl. | Pseudovivipary | Leong-Škorničková (pers. comm.) |
Z. singapurense Škorničk. | Pseudovivipary |
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The genus Hedychium (more than 80 species, see
Although the name Hedychium is more than 230 years old (
List of characters used to resolve the taxonomic identifications of plants in Figures
Taxon | Nature of lamina (abaxial) | Midrib type (adaxial) | Inflorescence height (cm) | Inflorescence density | Colour (labellum and filament) | Length of corolla segments (cm) |
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H. elatum | not pulverulent | faintly grooved | >30 | dense to moderately dense | labellum pinkish-white with red centre; filament reddish-pink | 3.5 |
H. gracile | not pulverulent | faintly grooved | 5–10 | lax to moderately dense | labellum creamy white with pale red base; filament bright red | 2.5 |
H. griffithianum | not pulverulent | faintly grooved | 15–22 | moderately dense | labellum creamy white with pale red base; filament bright red | 2.5 |
H. speciosum var. gardnerianum | pulverulent | deeply grooved | 30–45 | dense to moderately dense | labellum lemon yellow; filament bright red | 2.5–3.6 |
For taxonomic clarity, the key morphological and ecological characters of the Hedychium taxa) are listed below where facultative vivipary has been observed. Voucher information is provided below as: collector name, voucher number, herbarium deposited.
1. Hedychium marginatum C.B.Clarke (Figs
Plant terrestrial, up to 1.5 m tall. Inflorescence conical; bracts imbricate; cincinni 3–6 flowers. Flowers orange-yellow, fragrant. Capsule elliptic, green and minutely hairy. Seeds many; aril red. The viviparous individual (bearing at least 10 seedlings on its dried infructescence) was observed along the Mokokchung-Tuensang Road, Mokokchung, Nagaland (26°19'59"N; 94°32'50"E) in August 2017 (Fig.
It is very common in the Indian states of Manipur and Nagaland (
Flowering period: August to October; fruiting from September to November.
2. Hedychium speciosum var. gardnerianum (Ker Gawl.) Sanoj & M.Sabu (Figs
Plant terrestrial, up to 2.5 m tall. Inflorescence cylindrical; bracts folded, folding supervolute; cincinni 2 flowers. Flowers lemon-yellow with bright red stamen, highly fragrant. Capsule oblong, green and glabrous. Seeds many; aril red. The viviparous individuals were found growing along the Shillong-Dawki Road in the East Khasi Hills district, Meghalaya (25°22'25"N; 91°52'37"E) in August 2016 and 2017 (Fig.
It has a wide distribution range covering Eastern Himalaya and NE India, especially the Indian states of Arunachal Pradesh and Meghalaya (
Flowering period: July to October; fruiting from September to November.
3. Hedychium thyrsiforme Buch.-Ham. ex Sm. (Figs
Plant terrestrial, up to 1.5 m tall. Inflorescence pyramidal; bracts folded, folding supervolute; cincinni 3–8 flowers. Flowers white, mildly fragrant. Capsule oblong, green and glabrous. Seeds many; aril red. The viviparous individual (bearing one seedling on its dried infructescence) was observed in Aizawl, Mizoram (23°43'48"N; 92°43'52"E) in July 2017 (Fig.
It grows very commonly in the Indian state of Mizoram. It was originally described from Nepal (
Flowering period: August to October; fruiting from September to November.
4. Hedychium urophyllum G.Lodd. (Figs
Plant terrestrial, up to 2.2 m tall. Inflorescence conical; bracts imbricate; bracts are found to retain water; cincinni 2–4 flowers. Flowers bright yellow, highly fragrant. Capsule elliptic, dark green and glabrous. Seeds many; aril red. The viviparous H. urophyllum was growing in a mixed pine forest at Sanmer along the Shillong-Elephant Falls Road, East Khasi Hills district, Meghalaya (25°32'47"N; 91°50'16"E) in June 2015 and August 2016 (Fig.
It is endemic to Meghalaya (
Flowering period: July to September; fruiting from September to November.
During the three year study in NE India, four different Hedychium taxa showing vivipary have been identified: H. marginatum, H. speciosum var. gardnerianum, H. thyrsiforme and H. urophyllum. However, current observations of vivipary in Hedychium cannot be strictly identified as true vivipary or cryptovivipary (
The factors leading to the incidence of facultative vivipary can be identified as a combination of climatic, ecological and physiological variables (
This multi-year observation of facultative vivipary in four Hedychium taxa suggests that facultative vivipary may be a more common reproductive strategy than that which is known so far. The immediate germination of seeds on the parent plant in at least four taxa also implies that recalcitrance of seeds (i.e. absence of dormancy) may be common in Hedychium (also true for other gingers, Leong-Škorničková, pers. com.). Recalcitrance has been suggested to be a common characteristic of plants growing in wet habitats (
The authors’ efforts to summarise vivipary sensu lato across Zingiberaceae from published literature showed that vivipary sensu stricto is absent and that all reported cases of vivipary in other gingers can also only be identified as “facultative vivipary” or pseudovivipary, as in the case of Hedychium. Other genera that display facultative vivipary (except in A. mutica) also show similar characters as observed in Hedychium that favour this reproductive strategy, such as persistent bracts, bract structure that may retain the seeds, and recalcitrant seeds. It was found that both facultative vivipary and pseudovivipary are common amongst gingers with pseudovivipary being more frequent only in Globba (Table
To understand if vivipary sensu lato is a convergent character in Hedychium, different types of vivipary were mapped on a preliminary molecular phylogenetic tree (modified from nrDNA ITS tree of
The authors thank the Ministry of Human Resources and Development (MHRD), the National Geographic Society for research funds to V. Gowda, IISER-Bhopal for the infrastructure, the Council for Scientific and Industrial Research (CSIR) for the senior research fellowship to A. Ashokan and the Heliconia Society International (HSI) for the field research grant to A. Ashokan. We also thank State Forest Departments of Arunachal Pradesh, Manipur, Meghalaya, Mizoram and Nagaland for research permits, Dr. Mark Newman (Royal Botanic Garden Edinburgh) for drawing our attention to the taxonomic error in the identity of H. elatum that appeared in the previous report and Dr. Jana Leong-Škorničková (Singapore Botanic Gardens) and Dr. Neeta Sarangthem for research inputs. We also appreciate the suggestions and advice from two reviewers and the subject editor Dr. Yasen Mutafchiev that has helped us improve the manuscript.