Inflorescence Research Articles

Ceratostema gualaquizensis (Ericaceae: Vaccinieae), a new species from Ecuador known from previously misidentified specimens and new insights on Ceratostema loucianae

A species of Ceratostema new to science from southern Ecuador, is described and illustrated as part of ongoing research on biodiversity in the Cordillera Real de Los Andes. Ceratostema gualaquizensis is distinguished by the convex leaves with folded margins at the base, and the axillary, solitary, and tubular flowers with a slightly 5-ribbed corolla that is magenta with apically black lobes. Furthermore, we provide additional information on the newly described Ceratostema loucianae. The taxonomic similarities of these two species are discussed and information about their distribution, habitat, and conservation status are provided. Both species are being sold and cultivated with erroneous/fictitious names by nurseries and private collections, information of which is provided in this paper.

In splendid isolation: a new cloud forest species expands the distribution of Myrceugenia (Myrtaceae) into Las Yungas and adds a new genus to the flora of Bolivia

Myrceugenia is a temperate or subtropical genus of c. 50 species with a disjunct distribution across South America. The ‘western’ species occur in central Chile and north-western Argentina with one species in the Juan Fernández Islands. The ‘eastern’ species occur in Uruguay, southern Brazil, and marginal regions of Argentina and Paraguay, reaching montane eastern Brazil (two isolated taxa in Central Brazil). It is hypothesized that Myrceugenia once grew across the temperate forests of southern South America, but that oceanic transgressions and the elevation of the Andes during the Miocene divided its populations as the forests retracted from the centre of the continent. The Las Yungas floristic province is a strip of cool, temperate forest that runs along the eastern slopes of the Andes from Venezuela to northern Argentina; Myrceugenia was not known to occur there. We report the discovery of a new species of Myrceugenia in southern Las Yungas (Bosque Tucumano Boliviano). It is distinct from all other species of the genus by the combination of solitary flowers, sub-ancipitate hypanthium, bilocular locules, and 12-13 clustered ovules. The phylogeny of Myrceugenia shows geographic structuring with three basal western clades and one derived eastern clade. The isolated taxa of Myrceugenia from Central Brazil were sisters, respectively, to the rest of the eastern clade and to one of its two subclades, suggesting that isolated taxa are relictual. The discovery of this species has made Myrceugenia the only genus of Myrtaceae to grow in the three cool, humid forests of southern South America.

1112. Pittosporum beecheyi Tuyama: Pittosporaceae

SummaryPittosporum beecheyi Tuyama, endemic to the Ogasawara (Bonin) Islands is described and illustrated; the species is known only from the Hahajima Island group. Key characters for the recognition of this species include the hairy ovary, the solitary flowers with curved pedicels, and the pendulous globose fruits that dehisce into three valves.

Transcriptomic analysis reveals differential gene expression patterns during cannabis leaf morphogenesis and phase transition

ABSTRACT Understanding the molecular mechanisms governing leaf morphogenesis and phase transition in Cannabis sativa is critical for optimizing its growth, development and yield. In this study, we conducted a comparative transcriptomic analysis to investigate the gene expression patterns associated with leaf development and the transition from vegetative to reproductive phases in cannabis plants. Following germination, cannabis plants display a distinct leaf developmental pattern. While the specific number of leaflets varies among cultivars, here we focused on the White Widow cultivar as a model. It showed an increase in the number of serrated leaflets from one (L1) to nine (L5) in a node-specific manner. Subsequently, the number of leaflets decreased from eight (L6) to three (L9). The transition from vegetative to reproductive phases, marked by the appearance of solitary flowers and a shift from opposite to alternate leaf phyllotaxy, occurred at node 7 and node 12, respectively. Analysis of gene expression revealed 1358 differentially expressed genes, with 1,182 genes showing differential expression across all leaves. Notably, several genes involved in leaf morphogenesis (e.g. YAB, AGO5, and TCP4) were found to be upregulated in compound leaves (L2) compared to simple leaves (L1), implying a role in leaflet formation and overall leaf morphology. Furthermore, several genes associated with phase transition and flowering (e.g. SPLs, ELFs, SOC1, and CEN-Like) exhibited specific expression patterns during the transition from vegetative to reproductive phases. These findings provide valuable insights into the genetic regulation of leaf morphogenesis and phase transition in cannabis.

Species delimitation in Xanthium sect. Acanthoxanthium (Heliantheae, Asteraceae) and the neglected species Xanthium argenteum

AbstractXanthium is a genus of annual herbaceous plants that stands out within Asteraceae for being wind‐pollinated, diclinous monoecious, and bearing solitary pistillate flowers in peculiar spiny structures (burs). Xanthium sect. Acanthoxanthium is native to South America and characterized by the presence of trifurcate spines at the base of the leaves. Past taxonomic treatments of the section have been contradictory, some recognising up to six species, others reducing all to a single polymorphic species. Altogether, 42 samples of X. sect. Acanthoxanthium were analysed, the vast majority taken from herbarium specimens between 20 and 160 years old. We sampled multiple specimens of X. spinosum from throughout its broad range as well as those taxa with narrower distributions, covering the whole range of morphological variation in the section. When possible, we included types and original material. We used Hyb‐Seq techniques to obtain information from about 1000 single‐copy nuclear genes and complete plastomes. Phylogenomic data were submitted to coalescent‐based species delimitation approaches (SPEEDEMON). Additionally, we performed geometric morphometric analysis of leaf outlines. The results strongly support the identification of four lineages in the section favouring the acceptance of four of the hitherto described species, i.e., X. ambrosioides, X. argenteum, X. catharticum, and X. spinosum. These results were to some extent corroborated by morphometric analyses. While X. ambrosioides was well distinct from X. spinosum based on leaf morphology, such difference was not observed between X. spinosum and X. catharticum. However, X. catharticum differs from X. spinosum in its ecological requirements, being a species rather adapted to high‐mountain environments of the Neotropics. Intriguingly, X. argenteum – a taxon described from a single herbarium collection – was also inferred as a species.

Amorphophallus samarensis (Araceae), a new species endemic to Samar Island, Eastern Visayas, Philippines

Amorphophallus samarensis is described as a new species from Paranas, Samar Island Natural Park, Samar Eastern Visayas, Philippines. A. samarensis resembles A. calcicola by having a solitary leaf, long peduncled solitary flower, cylindric female zone, ovary depressed, disk shape, slightly distant ovaries, and absence of staminode. It differs from A. calcicola by having the rachis winged at the distal part of the leaf, pale to dark maroon slightly depressed globose capitate stigma, style color, length of spadix, and truncate anther. The new species is considered Critically Endangered (CR) based on IUCN guidelines due to persistent anthropogenic activities. There are 30 individual plants encountered in the locality with less than 100 sq. km area of occupancy with an observed threat.

Inflorescence development in female cannabis plants is mediated by photoperiod and gibberellin.

In cannabis seedlings, the initiation of solitary flowers is photoperiod-independent. However, when cannabis reaches the adult stage, short-day photoperiod (SD) triggers branching of the shoot apex and a reduction in internode length, leading to development of a condensed inflorescence. We demonstrate that SD affects cannabis plants in two distinct phases: the first includes rapid elongation of the internodes and main stem, and occurring from Day 5 to Day 10 of plant cultivation under SD; in the second phase, elongation of newly developed internodes ceases, and a condensed inflorescence is formed. Exposure of plants to alternating photoperiods revealed that inflorescence onset requires at least three consecutive days of SD, and SD is consistently required throughout inflorescence maturation to support its typical condensed architecture. This photoperiod-dependent morphogenesis was associated with a decrease in gibberellin (GA4) and auxin levels in the shoot apex. Reverting the plants to a long-day photoperiod (LD) increased GA4 and auxin levels, leading to inflorescence disassembly, internode elongation, and subsequent resumption of LD growth patterns. Similar developmental patterns were observed under SD following the application of exogenous GA (and not auxin), which also impeded inflorescence development. Nevertheless, additional studies will help to further evaluate auxin's role in these developmental changes. We propose a crucial role for GA in sexual reproduction and inflorescence development in female cannabis by mediating photoperiod signaling in the inflorescence tissues.

An overview of floral and vegetative evolution in the Asian clade of Bulbophyllum (Orchidaceae)

Background and aims – Bulbophyllum, the largest genus in Orchidaceae, exhibits a diverse morphology in both reproductive and vegetative characters. While trait diversity and evolution has been extensively studied in Malagasy species and within the Cirrhopetalum alliance clade, the evolution of reproductive and vegetative characters at the whole level of the Asian clade remains largely unexplored. Material and methods – We reconstructed the phylogeny of approximately 11% of all Asian Bulbophyllum species using Bayesian inference and maximum likelihood estimation based on nuclear (ITS) and chloroplast (matK, psbA-trnH) DNA sequence data. This phylogenetic framework allowed us to examine the evolution of two vegetative and four floral characters through ancestral state reconstruction. Key results and conclusion – The ancestral character states of the Asian clade of Bulbophyllum include a single leaf, distinct pseudobulbs, multiple-flowered inflorescences, and lateral and dorsal sepals similar in length. One-leaved pseudobulbs evolved into two-leaved pseudobulbs multiple times. Distinct pseudobulbs gave rise to indistinct pseudobulbs twice. Multiple-flowered inflorescences shifted to solitary flowers and 2–3-flowered inflorescences multiple times, with some instances of evolutionary reversal. Lateral sepal elongation also presents a convergent evolutionary scenario.

International Biological Flora: Trapa natans†

Abstract This account presents information on all aspects of the biology of Trapa natans L. (water caltrop and water chestnut) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the International Biological Flora: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, conservation and global heterogeneity. The water caltrop is an annual herbaceous hydrophyte rooted in the sediment of water bodies, forming flexuous underwater stems that create a buoyant, light‐capturing leaf rosette at the water surface. The submerged stem nodes additionally bear linear leaves. These are replaced by photosynthetically active, pinnately branched structures and unbranched adventitious roots early on, which complement previously established roots on the hypocotyl, altogether facilitating anchorage, nutrient and water absorption, aeration and capture of subsurface irradiance. Solitary flowers pollinated primarily through autogamy and incidentally through entomophily give rise to a fully developed edible single‐seeded drupe with two to four barbed horns. Fruits are dispersed with the help of hydrochory, epizoochory and anthropochory. Throughout its lowland, global temperate, subtropical and tropical distribution in Eurasia and Africa, the thermophilic macrophyte is found in shallow, sun‐exposed, nutrient‐rich freshwater bodies with low‐velocity flows and steady water levels. These offer slightly acidic to mildly basic conditions. The accompanying soft substrate is usually characterized by a high organic matter content. Regularly co‐occurring with other macrophytes, some of which are also of conservation concern, such as those in rare stands of the association Trapetum natantis in Europe, the water caltrop has at times been outcompeted, though it may form monodominant stands, due to several competitive features. Formerly widespread in Europe, T. natans is today recognized as a rare, strictly protected macrophyte. It has been introduced to Australia and North America; on the latter continent, its naturalization, spread and aggressive overgrowth have led to extensive control efforts. Having been used as a crop since Neolithic times, it is still exploited in Asia for means of food production, phytoremediation, ornamental purposes, medication and alternative uses.

A taxonomic revision of GarciniasectionGarcinia (Clusiaceae) in Thailand.

GarciniasectionGarcinia (Clusiaceae) is revised for Thailand with three species and one variety, i.e., two native species: G.celebica and G.exigua, and one cultivated species: G.mangostanavar.mangostana. Detailed morphological descriptions, illustrations, and an identification key to the species are presented, along with notes on distributions, habitats and ecology, phenology, conservation assessments, etymology, vernacular names, uses, and specimens examined. The section is recognized by its terminal inflorescences of simple cymes, or sometimes a solitary flower; flowers with 4 sepals and 4 petals; male flowers often with a pistillode, and stamens united into a single 4-lobed or 4-angled bundle, and with 2-thecous anthers; usually multilocular ovaries and stigmas with distinct or weak lobes and smooth or rough; and fruits with a smooth surface. Three associated synonyms of G.celebica: G.ferrea, G.basacensis, and G.hombroniana, are lectotypified here in a second-step. In Thailand, Garciniacelebica is found in a very wide variety of habitats, at elevations of 0-1,500 m amsl., and is known to be naturally distributed in all floristic regions. G.exigua is found in dry evergreen forest on limestone hills and in littoral dry evergreen forest on limestone hills, at elevations of 50-100 m amsl. in Krabi Province, the peninsular region. G.mangostanavar.mangostana is found only in cultivation. Garciniaexigua has a conservation status of Vulnerable [VU B2ab(iii)] and the other two species have a conservation status of Least Concern [LC]. The fleshy pulp surrounding the seeds of two species, G.celebica and G.mangostanavar.mangostana is edible and has a sweet-sour taste.

Phyllanthus novofriburgensis and P. pedrosae, two new species of Phyllanthus subsect. Clausseniani (Phyllanthaceae) from Southeastern Brazil

Phyllanthus novofriburgensis J.C.R.Mendes, J.M.A.Braga & Fraga sp. nov. and P. pedrosae J.C.R.Mendes, J.M.A.Braga & Fraga sp. nov. are new species of Phyllanthaceae described from the Brazilian Atlantic Forest and Brazilian Cerrado, respectively. Phyllanthus novofriburgensis resembles P. acutifolius Poir. ex Spreng., P. hypoleucus Müll.Arg. and P. lilliputianus J.C.R.Mendes, J.M.A.Braga & Fraga, sharing ovate, elliptical, and lanceolate leaf blades. However, it can be distinguished by its pendulous habit, often with sinuous branches and lanceolate leaf blades with characteristically revolute margins. Phyllanthus pedrosae exhibits morphological similarities with P. claussenii Müll.Arg. due to its subshrubby and prostrate habit. It is distinghuished by the unisexual inflorescence with cymules composed of one or two staminate flowers proximally positioned in the axil of the branches and solitary pistillate flowers distally situated, and the 5-merous calyx in the staminate and pistillate flowers. Both new species are classified in Phyllanthus subgen. Phyllanthus sect. Phyllanthus subsect. Clausseniani G.L.Webster, primarily due to the deeply emarginate anthers. Notes on their geographical distribution and habitat are provided, as well as a key to the species of Phyllanthus from Southeastern Brazil.

Impatiens alboarenicola, a new species of Balsaminaceae from north-western Madagascar

A new species of Impatiens, I. alboarenicola (Balsaminaceae), is described and illustrated from Ankarafantsika National Park, north-western Madagascar. This species is similar to I. barthlottii and I. tsingycola in leaf and flower shape, but clearly distinguished from the former by its shorter stature, absence of a tuber at the stem base, solitary (rarely 2) flowers in the axils of leaves, and smaller flowers, and from the latter by its smaller leaf blades with fewer pairs of teeth on the dentate leaf margin, solitary (rarely 2) flowers in the axils of leaves, and saccate spur-like projection located at ca. 5 mm below the apex of the lower petal lobe of the lateral united petals (vs. at the apex of the lower petal lobe).

Autochthonous grape varieties in the Lower Don Region

This article describes modifi cation changes in the phenotypic traits of grape varieties, including the number of normally developed shoots and infl orescences, the average bunch weight, and grape yield under the infl uence of unstable weather conditions. The research was carried out in the moderate continental climate of the Lower Don region in the period from 2013 to 2022. The average annual air temperature ranged from +10.2 to +11.6 °C, with the climatic norm being +10.4 °C. In the period of active vegetation (May–September), the temperature ranged from +21.2 to +22.7 °C, with the norm being 18.1 °C. The maximum temperature ranged from +37.2 to +40.0 °C, with the norm being +40.0 °C. In winter, during the plant dormancy period (December–February), the average air temperature varied from 0.6 to minus 2.6 °С, with the norm being about minus 2.4 °С. The annual precipitation varied from 292 to 693 mm, with the norm being 548 mm. During the vegetation period of grapes, atmospheric precipitation by the years of observation varied from 99 to 359 mm, with the norm being 177 mm. The aim was to establish the limits of modifi cation variability of phenotypic traits under the infl uence of the unstable moderate continental climate of the Lower Don Region. The research objects were autochthonous grape varieties, including ‘Varyushkin’, ‘Krasnostop’ ‘Zolotovsky’, ‘Kumshatsky Belyi’, ‘Plechistik’, ‘Sibirkovy’, and ‘Tsimlyansky Chernyi’. The reaction norm and modifi cation changes of the phenotypic traits of grape plants under the infl uence of natural conditions in their habitats were studied. The autochthonous grape varieties in contrasting weather conditions exhibited individual and varietal specifi city in terms of reaction norm and adaptability. According to the variability of phenotypic traits and adaptive potential, the varieties were ranked in the following descending order: ‘Plechistik’, ‘Krasnostop Zolotovsky’, ‘Varyushkin’, ‘Kumshatsky Belyi’, ‘Sibirkovy’, and ‘Tsimlyansky Chernyi’. The genotypes ‘Plechistik’, ‘Krasnostop Zolotovsky’, ‘Varyushkin’, and ‘Kumshatsky Belyi’ with their high adaptive potential for formation of stable vine plantations are recommended for developing stable grape plantations in the conditions of the Lower Don region.

Relictithismia kimotsukiensis, a new genus and species of Thismiaceae from southern Japan with discussions on its phylogenetic relationship.

The family Thismiaceae, known as "fairy lanterns" for their urn- or bell-shaped flowers with basally fused tepals, consists of non-photosynthetic flowering monocots mainly in tropical regions, extending into subtropical and temperate areas. Here, we propose a new mycoheterotrophic genus, Relictithismia Suetsugu & Tagane (Thismiaceae), with its monotypic species Relictithismia kimotsukiensis Suetsugu, Yas.Nakam. & Tagane from Kimotsuki Mountains in the Osumi Peninsula, Kagoshima Prefecture, Kyushu Island, southern Japan. Relictithismia resembles Haplothismia Airy Shaw in having a cluster of tuberous roots, a feature previously observed only in this genus within the family Thismiaceae. However, it differs in having solitary flowers (vs. 2-6-flowered pseudo-raceme in Haplothismia), anther thecae largely separated (vs. connate), and the presence of an annulus (vs. absent). Additionally, Relictithismia differs from the geographically overlapping genus Thismia Griff. in its stamen structure and the position of the annulus. In Relictithismia, the stamens lack connectives, and its free filaments arise from the annulus located inside the perianth mouth, while in Thismia, the stamens typically have connate connectives, forming a staminal tube pendulous from the annulus located at the mouth of the floral tube. Our morphological and phylogenetic data indicated that R. kimotsukiensis holds an early-diverging position within the family, situated outside the Old World Thismia clade. This paper offers an extensive description and color photographs of R. kimotsukiensis, complemented by notes on its phylogenetic relationship and evolutionary history.

Development and evolution of the Asteraceae capitulum.

Asteraceae represent one of the largest and most diverse families of plants. The evolutionary success of this family has largely been contributed to their unique inflorescences, capitula that mimic solitary flowers but are typically aggregates of multiple florets. Here, we summarize the recent molecular and genetic level studies that have promoted our understanding of the development and evolution of capitula. We focus on new results on patterning of the enlarged meristem resulting in the iconic phyllotactic arrangement of florets in Fibonacci numbers of spirals. We also summarize the current understanding of the genetic networks regulating the characteristic reproductive traits in the family such as floral dimorphism and differentiation of highly specialized floral organs. So far, developmental studies in Asteraceae are still limited to a very narrow selection of model species. Along with the recent advancements in genomics and phylogenomics, Asteraceae and its relatives provide an outstanding model clade for extended evo-devo studies to exploit the morphological diversity and the underlying molecular networks and to translate this knowledge to the breeding of the key crops in the family.

<i>CAMELLIA HOAANA</i> (THEACEAE, SECTION <i>CORALLINA</i>), A NEW SPECIES FROM BU GIA MAP NATIONAL PARK IN SOUTHERN VIETNAM

Camellia hoaana, a new species of the Camellia sect. Corallina (Theaceae) from Bu Gia Map National Park, Vietnam, is described and illustrated. Morphological features of this species are young branches pubescent and glabrescent. Leaves elliptic to obovate-elliptic; apex bluntly cuspidate, base wide cuneate; above dark green, shiny and glabrous; below paler green and sparsely pubescent along midrib; petiole sparsely pubescent. Flowers solitary or geminate, axillary or terminal; pedicel pubescent. Bracteole 1 (or none),pubescent on both sides, persistent. Sepals 4–5(–6), pubescent on both sides, persistent. Petals 5–6, white, outermost 1–2 pubescent at the apex on both sides, the rest glabrous on both sides. Androecium numerous, 2–3 whorls, glabrous. Ovary 3-locular, white silky tomentose; styles 3, free to the base, glabrous. Capsule subglobose, sparsely pubescent, furfuraceous. Seeds 1–2 per locule, semiglobose or globose, densely brown villous. This new species is assessed as Data Deficient (DD) according to the IUCN categories and criteria.

Acmella oleracea (L.) R.K. Jansen essential oils: Chemical composition, antioxidant, and cytotoxic activities

Acmella oleracea is an important food and medicinal plant in the Amazon; it is used to treat toothaches, hepatitis, malaria, fever is also described as an anticancer plant. This work reports for the first time the comparison of chemical profiles, antioxidant, and cytotoxic capacities of inflorescence (INF) and leaf (LEA) A. oleracea essential oils (EOs) obtained by hydrodistillation (HD) and steam distillation (SD). The essential oils were obtained by hydrodistillation and steam distillation and analyzed by GC and GC-MS. The antioxidant potential was evaluated by the co-oxidation method of the β-carotene/linoleic acid, and the cytotoxic activity against healthy human embryonic kidney (HEK-293), gastric ascites (AGP-01), melanoma (SK-MEL-19), lung carcinoma (A549) malignant cell lines by the MTT method. The essential oils obtained from INF by HD and SD showed the highest yields (HD = 0.68; SD = 0.5%). The monoterpene hydrocarbons (0–49.97%) and sesquiterpene hydrocarbons (25.79–50.63%) were predominant in the analyzed oils. The main constituents (>10%) identified in the EO samples were caryophyllene oxide (0.3–28.11%), E-caryophyllene (6.71–27.31%), myrcene (0–25.03%), germacrene D (0.06–19.56%), guaiol (0–14.23%), 1-pentadecene (0–13.88%), and β-pinene (0–10.04%). The chemometric analysis displayed the formation of three distinct groups of chemical compositions as follows: group I, LEA EOs (HD and SD); group II, INF EO (HD); and group III, INF EO (SD). The INF (14.3%) and LEA (9.0%) EOs showed antioxidant action with no significant difference (p < 0.05). The INF EO (HD) showed higher cytotoxicity against the malignant lineages of gastric ascites (IC50 5.31 μg/mL), melanoma (IC50 6.43 μg/mL), while the LEA EO (SD) was more cytotoxic against the lung carcinoma cell line (13.39 μg/mL), and higher toxicity was also observed against the healthy embryonic kidney cell line (IC50 5.14 μg/mL). Acmella oleracea is chemically influenced by the volatile extraction methods, and this influences on the antioxidant or cytotoxic capacity of the species.

Four new species of Perilimnastes (Sonerileae, Melastomataceae) from Vietnam.

Perilimnastes is a genus currently treated in the polyphyletic Phyllagathis. Recent phylogenomic analyses have identified a morphologically cohesive lineage referred to as the Phyllagathis (raphides) clade, which should be excluded from Phyllagathis and treated as a distinct genus under the name Perilimnastes. Morphological and phylogenomic data have confirmed that four new species collected from Vietnam are part of the Phyllagathis (raphides) clade. They are described herein as Perilimnastesmultisepala, P.setipetiola, P.uniflora, and P.banaensis. Perilimnastesmultisepala is phylogenetically closest to Phyllagathissetotheca, and morphologically to P.fruticosa and P.stenophylla, but is distinct in the 4- to 8-lobed calyx, 28 × 9 mm, apically long acuminate petals, and 1-2 mm pedicel at fruiting stage. Perilimnastessetipetiola, P.uniflora, and P.banaensis are phylogenetically most closely related. Perilimnastesuniflora is characterized by its prostrate habit, small size, glabrous, obovate to obovate-lanceolate leaf blade, and solitary flower. Perilimnastessetipetiola and P.banaensis resemble each other in habit, leaf size and shape, and sessile or near sessile inflorescences but can be easily distinguished by the indumentum of the stems and leaves.

&lt;i&gt;CAMELLIA PYRIFORMIS&lt;/i&gt; (THEACEAE, SECTION &lt;i&gt;CALPANDRIA&lt;/i&gt;), A NEW SPECIES FROM NORTHERN VIETNAM

Camellia pyriformis is described, illustrated, and placed in section Calpandria. Morphological features of this new species are young branches villous; leaves above pubescent, a long midrib, below pubescent; petiole falcate, densely villous; flowers solitary or geminate; pedicel very short, pubescent; bracteoles sparsely pubescent on both sides; sepals, pubescent on both sides; petals, white, glabrous; androecium 5–6 stamens, filaments completely united to form a truncated cone, glabrous, basal adnate to the petal, shallowly dentate at the apex, each filament bearing an anther; gynoecium 3-locular, densely white silky strigose tomentose, styles glabrous; capsule pyriform, pubescent; seed broad pyriform, densely villous

Morphological Characterization of Cannabis sativa L. Throughout Its Complete Life Cycle.

This study extensively characterizes the morphological characteristics, including the leaf morphology, plant structure, flower development, and trichome features throughout the entire life cycle of Cannabis sativa L. cv. White Widow. The developmental responses to photoperiodic variations were investigated from germination to mature plant senescence. The leaf morphology showed a progression of complexity, beginning with serrations in the 1st true leaves, until the emergence of nine leaflets in the 6th true leaves, followed by a distinct shift to eight, then seven leaflets with the 14th and 15th true leaves, respectively. Thereafter, the leaf complexity decreased, culminating in the emergence of a single leaflet from the 25th node. The leaf area peaked with the 12th leaves, which coincided with a change from opposite to alternate phyllotaxy. The stipule development at nodes 5 and 6 signified the vegetative phase, followed by bract and solitary flower development emerging in nodes 7-12, signifying the reproductive phase. The subsequent induction of short-day photoperiod triggered the formation of apical inflorescence. Mature flowers displayed abundant glandular trichomes on perigonal bracts, with stigma color changing from whitish-yellow to reddish-brown. A pronounced increase in trichome density was evident, particularly on the abaxial bract surface, following the onset of flowering. The trichomes exhibited simultaneous growth in stalk length and glandular head diameter and pronounced shifts in color. Hermaphroditism occurred well after the general harvest date. This comprehensive study documents the intricate photoperiod-driven morphological changes throughout the complete lifecycle of Cannabis sativa L. cv. White Widow. The developmental responses characterized provide valuable insights for industrial and research applications.