Matti A. Niissalo

Summary: We describe and illustrate Nervilia singaporensis Niissalo, a small Southeast Asian terrestrial orchid which has only been collected in Singapore. This is a mostly cleistogamous species, superficially similar to other cleistogamous species in the Nervilia adolphi/punctata species alliance. Most flowers never open but develop immediately to seed capsules. Unlike many species in the genus, N. singaporensis lacks strict vegetative, dormant and flowering seasons and flowering and fruiting plants can be found year‐round, sometimes simultaneously with the leaves. This genus is poorly understood in Malesia, which could explain why this species has not been recorded in other countries.

Summary: A description and illustrations are provided for Hanguana neglecta Škorničk. & Niissalo, an interesting forest herb known only from Singapore and Peninsular Malaysia. This species can be readily identified by its small habit with predominantly upright leaves, trilobed clover leaf‐shaped stigma, black fruits, and characteristic seeds that feature a deep excavation and a wedge‐shaped ostiole.

Summary: Papilionanthe Miss Joaquim ‘Agnes’, an artificial hybrid between Papilionanthe teres (Lindl.) Schltr. and Papilionanthe hookeriana (Rchb.f.) Schltr., is described and illustrated. This hybrid, still commonly known as Vanda Miss Joaquim, originated in Singapore and was selected as the country's national flower in 1981. It is notable for its vibrant pink‐purple flowers borne on inflorescences, its ability to bloom year‐round in tropical climates, and its historical importance to Singapore's horticultural and cultural heritage.

Summary: A description and illustrations of Zingiber singapurense Škorničk., a critically endangered ginger, are presented with notes on cultivation and recent conservation efforts. The species is endemic to Singapore and known under the common name, SINGAPORE GINGER. Key characters for the recognition of this species include narrow dark green leaves and an inflorescence composed of a peduncle and an orange‐red fusiform spike bearing pale yellow flowers. Interestingly, this species is pseudoviviparous, producing young plantlets at the end of mature and old leafy shoots, which readily root upon contact with the ground.

Studies investigating the evolution of flowering plants have long focused on isolating mechanisms such as pollinator specificity. Some recent studies have proposed a role for introgressive hybridization between species, recognizing that isolating processes such as pollinator specialization may not be complete barriers to hybridization. Occasional hybridization may therefore lead to distinct yet reproductively connected lineages. We investigate the balance between introgression and reproductive isolation in a diverse clade using a densely sampled phylogenomic study of fig trees (Ficus, Moraceae). Codiversification with specialized pollinating wasps (Agaonidae) is recognized as a major engine of fig diversity, leading to about 850 species. Nevertheless, some studies have focused on the importance of hybridization inFicus, highlighting the consequences of pollinator sharing. Here, we employ dense taxon sampling (520 species) throughout Moraceae and 1,751 loci to investigate phylogenetic relationships and the prevalence of introgression among species throughout the history ofFicus. We present a well-resolved phylogenomic backbone forFicus, providing a solid foundation for an updated classification. Our results paint a picture of phylogenetically stable evolution within lineages punctuated by occasional local introgression events likely mediated by local pollinator sharing, illustrated by clear cases of cytoplasmic introgression that have been nearly drowned out of the nuclear genome through subsequent lineage fidelity. The phylogenetic history of figs thus highlights that while hybridization is an important process in plant evolution, the mere ability of species to hybridize locally does not necessarily translate into ongoing introgression between distant lineages, particularly in the presence of obligate plant–pollinator relationships.

Lowiaceae (order Zingiberales) is a small family of forest herbs in Southeast Asia. All species belong to the genus Orchidantha. They are known for possessing orchid-like flowers that are smelly, apparently mimicking dead animals, feces, or mushrooms. Little is known of the biogeographic patterns or character evolution of the family. We sampled the family extensively, including many recently discovered species, and reconstructed the phylogeny of the family using HybSeq with Lowiaceae-specific RNA baits. Our phylogenetic reconstructions confirm that the family is most closely related to Strelitziaceae, and that species with dark, foul-smelling flowers form a grade in which a clade of species with paler flowers are embedded. The pale-flowered species produce a distinct odor, resembling edible mushrooms. Apart from a single species, the species from Borneo form a clade, and the same is true for Indochinese species. The remaining species form a more widespread clade. A biogeographic analysis shows that the distribution of Lowiaceae can explained by vicariance and gradual dispersal from a shared ancestral range of Borneo and Indochina. There is no evidence of long-distance dispersal, only a later extension in distribution to Peninsular Malaysia which coincides with the presence of a land bridge. Different directions of spread are possible, but none require long-distance dispersal. The results are consistent with the geological history of Southeast Asia. In particular, the relatively early isolation between Indochina and Borneo could be explained by the presence of a sea barrier that developed 10–15 MYA, and the continuous movement of plant species between Borneo and Peninsular Malaysia could be explained by a land bridge that existed until c. 5 MYA. The lack of an extensive land bridge with a suitable habitat may explain the absence of this genus from Sumatra and other Indonesian islands aside from Borneo. The strict reliance on a continuous habitat for the range expansion of Lowiaceae can be explained by their fruits and seeds, which lack obvious adaptations for long-distance dispersal. The inability to disperse to new areas may also explain why the extant species have very restricted distributions.

As part of a project to sample tissue from all native vascular plants in Bukit Timah Nature Reserve, we collected material from four species that have not been previously recorded in Singapore. Of these, Nervilia singaporensis Niissalo has already been described as a new species, native to Singapore. Two species, Lepidogyne longifolia (Blume) Blume (Orchidaceae) and Ptyssiglottis kunthiana (Wall. ex Nees) B.Hansen (Acanthaceae), which are reported here, belong to genera that have not previously been recorded in Singapore. Based on their collection history in the region and their habitat in Bukit Timah Nature Reserve, we consider them native to Singapore. The fourth new record, Plectocomiopsis cf. corneri Furtado (Arecaceae), also reported here, is a new species record for Singapore, but based on the collection history of the species and its only known locality in Singapore, we consider it introduced. The nomenclature and history of these species are discussed and we designate lectotypes for several names that are relevant to these species: Neottia longifolia Blume, Lepidogyne sceptrum Schltr., Polytrema aequale Ridl., Polytrema aequale Ridl. var. minor Ridl. and Polytrema vulgare C.B.Clarke. We also designate a neotype for Lepidogyne minor Schltr.

The abundance of apomixis in tropical plant genera is poorly understood, and this affects the understanding of speciation and evolution. Hanguanaceae is a tropical monogeneric, dioecious plant family. All but two species are solitary herbs with no capability to spread vegetatively. Viable seeds are often produced when males have not been observed. Our aim was to investigate the presence of apomixis in Hanguana. We used reduced representation genomics to study phylogenetics and genetic variability in all populations of Hanguana in Singapore. We measured genome sizes and estimated ploidy levels in 10 species. Almost all taxa tested were genetically uniform (uniclonal) regardless of the extent of their distribution. The distribution of single clones over distinct localities supports our hypothesis of apomictic reproduction. Only one sexually reproducing native species was detected. Triploid and pentaploid states support our hypothesis that the type of apomixis in Hanguana is gametophytic. Population genomics tools offer a quick and cost-effective way of detecting excess clonality and thereby inferring apomixis. In the case of Hanguana, the presence of male plants is a strong indicator of sexual reproduction, whereas genome triplication is indicative of apomictic reproduction.

Gordonia penangensis Ridl. is a rainforest tree native to Peninsular Malaysia and Singapore. Here we provide the complete plastome from a collection made in Singapore. The plastome sequence is 156,915 bp long with a large single copy, a small single copy and two inverted repeat regions of length 86,669, 18,200 and 26,023 bp, respectively. A total of 114 unique genes were identified, including 80 coding genes (seven in two copies), four ribosomal RNAs (all in two copies) and 30 transfer RNAs (seven in two copies). The plastome architecture and gene content are very similar to previously published plastomes from genus Polyspora, to which most Asian Gordonia species have been transferred. Phylogenetic analyses using maximum likelihood were carried out on CDS regions from complete plastomes of 88 taxa, including five out of the 43 species currently recognised to be from Polyspora. A nuclear DNA phylogeny based on ITS sequences was also generated. Our results support the view that all Asian species of Gordonia are best treated as Polyspora. Four new combinations, Polyspora penangensis (Ridl.) Niissalo & L.M.Choo, Polyspora singaporeana (Wall. ex Ridl.) Niissalo & L.M.Choo, Polyspora obtusa (Wall. ex Wight) Niissalo & L.M.Choo and Polyspora ovalis (Korth.) Niissalo & L.M.Choo are made. Three lectotypes are also designated here.