Inflorescence Research Articles

Revision and new species of the African genus Mischogyne (Annonaceae)

SummaryMischogyne (Annonaceae, tribe Monodoreae) is a genus of small- to medium-sized tropical trees and shrubs. It is characterised by a combination of: (1) stamens and carpels on a more or less extended torus; (2) carpels divergent from each other at the apex of the torus above the anthers; (3) anthers linear and anther connectives not expanded above the thecae; (4) inflorescences extra-axillary (or sometimes terminal in M. michelioides) with usually solitary flowers; (5) petals reflexed at anthesis (except M. michelioides), and (6) prominent reticulate tertiary veins. The genus is found in the lowland tropical rainforests of Africa with annual precipitation of 1000 – 4000 mm and in the dry coastal foothills of Angola. Five species and one variety of Mischogyne are recognised. One newly discovered species from the Eastern Arc Mountains, M. iddii, is described. The variety M. elliotiana var. glabra is reduced into synonymy with M. elliotiana var. elliotiana. Mischogyne elliotiana var. gabonensis is raised to species level as M. gabonensis. Specimens from the Congo are recognised as a new species, M. congensis. Preliminary conservation status assessments are provided for each species, as well as an identification key and detailed species descriptions. An unusual distribution pattern for the genus is discussed: dry coastal Angola as well as West, Central and East African wet forest.

Extrafloral nectaries producing rewards for pollinator attraction in Acacia longifolia (Andr.) Willd.

ABSTRACT Evidence is presented that the extrafloral nectaries (EFN) of Acacia longifolia Andr. Willd. serve as sources of rewards that attract pollinating insects. Bees and wasps feed at EFN often crawling over inflorescences and passively vectoring pollen as birds do on A. terminalis. The position in relation to inflorescences, timing of secretion in relation to flowering, and visitation behavior of pollinating insects support this hypothesis.

Mitrephoramonocarpa (Annonaceae): a new species from Surat Thani Province, Peninsular Thailand.

A new species, Mitrephoramonocarpa R.M.K.Saunders & Chalermglin, sp. nov. (Annonaceae), is described from Surat Thani Province in Peninsular Thailand. It resembles two other species, M.alba Ridl. and M.keithii Ridl., with which it is broadly sympatric, but can be distinguished by its solitary flowers (not borne in thyrsoid inflorescences as in most other Mitrephora species), single carpel per flower (and hence single monocarp per fruit) and the lack of a monocarp stipe. A key to the nine Mitrephora species in Thailand is provided.

Overexpression of RICE FLOWERING LOCUS T 1 (RFT1) Induces Extremely Early Flowering in Rice.

RICE FLOWERING LOCUS T 1 (RFT1) is a major florigen that functions to induce reproductive development in the shoot apical meristem (SAM). To further our study of RFT1, we overexpressed the gene and examined the expression patterns of major regulatory genes during floral transition and inflorescence development. Overexpression induced extremely early flowering in the transgenics, and a majority of those calli directly formed spikelets with a few spikelets, thus bypassing normal vegetative development. FRUITFULL (FUL)-clade genes OsMADS14, OsMADS15, and OsMADS18 were highly induced in the RFT1-expressing meristems. OsMADS34 was also induced in the meristems. This indicated that RFT1 promotes the expression of major regulatory genes that are important for inflorescence development. RFT1 overexpression also induced SEPALLATA (SEP)-clade genes OsMADS1, OsMADS5, and OsMADS7 in the greening calli before floral transition occurred. This suggested their possible roles at the early reproductive stages. We found it interesting that expression of OsFD1 as well as OsFD2 and OsFD3 was strongly increased in the RFT1-expressing calli and spikelets. At a low frequency, those calli produced plants with a few leaves that generated a panicle with a small number of spikelets. In the transgenic leaves, the FUL-clade genes and OsMADS34 were induced, but SEP-clade gene expression was not increased. This indicated that OsMADS14, OsMADS15, OsMADS18, and OsMADS34 act immediately downstream of RFT1.

Architecture and Florogenesis in Female Cannabis sativa Plants.

The inflorescence is the main product of medical cannabis. Hundreds of specialized metabolites with potential bioactivity are produced and accumulated in the glandular trichomes that are highly abundant mainly on female inflorescences. Understanding the morphophysiological and genetic mechanisms governing flower and inflorescence development is therefore of high scientific and practical importance. However, in-depth investigations of cannabis florogenesis are limited. Cannabis producers and researchers consider long photoperiod to be “non-inductive” or “vegetative,” but under these growth conditions, the development of solitary flowers and bracts in shoot internodes clearly indicates that the plant cannot be defined as vegetative or non-inductive in the classical sense. Most probably, induction of solitary flowers is age-dependent and controlled by internal signals, but not by photoperiod. Short photoperiod induces intense branching, which results in the development of a compound raceme. Each inflorescence consists of condensed branchlets with the same phytomer structure as that of the larger phytomers developed under long day. Each phytomer consists of reduced leaves, bracts, one or two solitary flowers, and an axillary shoot (or inflorescence). Therefore, the effect of short photoperiod on cannabis florogenesis is not flower induction, but rather a dramatic change in shoot apex architecture to form a compound racemose inflorescence structure. An understanding of the morphophysiological characteristics of cannabis inflorescence will lay the foundation for biotechnological and physiological applications to modify architecture and to maximize plant productivity and uniformity in medical Cannabis.

TWO NEW SEDGES (CAREX SECT. ACROCYSTIS, CYPERACEAE) FROM NORTHWESTERN MEXICO AND SOUTHERN CALIFORNIA

Carex bajacalifornica Zika is described from five populations in the mountains of northern Baja California, Mexico, in the Sierra de Juarez and Sierra de San Pedro Martir. It is distinguished from Carex rossii Boott by its short inflorescence bract, abbreviated perigynium beak shorter than the stipe, and nerved perigynium faces. Carex cryptosperma Zika, D.S. Bell, and L.J. Gross is described from 12 populations in southern California, in the San Bernardino, San Gabriel, and San Jacinto Mountains. Carex cryptosperma differs from Carex xerophila Janeway & Zika in its relatively short perigynium stipe and relatively long perigynium beak. The new species are illustrated and mapped, and a key is presented to members of Carex sect. Acrocystis in the states of California and Baja California.

A taxonomic revision of Notothlaspi (Brassicaceae), a specialist alpine genus from New Zealand

The New Zealand endemic alpine genus Notothlaspi comprises three species from the South Island mountains. Notothlaspi australe and the newly described N. viretum occur on rock bluffs and outcrops and their associated stony soils. Notothlaspi australe occurs in Nelson, Marlborough and north Westland, northern South Island, and N. viretum is endemic to the highest peaks of Red Hills, Marlborough, where it occurs on ultramafic soils. Notothlaspi viretum is segregated from the sympatric N. australe by its numerous, closely placed rosettes that form compact cushions and the leaves are linear to linear-narrowly lanceolate. These two species are distinguished from the scree-specialist, rosette forming, monocarpic N. rosulatum by their perennial growth habit, forming cushions with branched stems, narrower leaves, axillary and solitary flowers, and smaller silicles. Notothlaspi rosulatum is known from Nelson, Westland, Marlborough, Canterbury and Otago. Notothlaspi rosulatum var. hursthousei and N. notabilis are treated as synonyms of N. rosulatum, and N. australe var. stellatum is placed as a synonym of N. australe. All names are typified and a key is provided.

Towards a Revision of Diastema within Central America

Diastema is a genus of flowering plants within the subtribe Gloxiniinae (Gesneriaceae). Some key characteristics of Diastemainclude a racemose flowering axis consisting of solitary flowers in the axils of bracts on the stems with condensed internodes, nectary consisting of 5 finger-like glands, and a distinctive bi-lobed stigma. Interestingly, there are currently only twenty described species and Diastemahas not been the focus of adequate research until now. I have collected a sufficient sample size of morphological and molecular data from both known and unknown species. Any new potential new species are compared to the appropriate type specimens to determine circumscription. Moreover, morphological studies focus on taxonomically useful vegetative and reproductive characters with special emphasis given to trichome structure and fruit shape. Molecular studies are focused on nuclear and chloroplast genes to ascertain if any hybridization has occured. Several samples of DNA are now ready to be sequenced for a more comprehensive understanding of the genus. The outcomes of this research will provide a baseline for conservation and governmental agencies to work from to protect the habitat where these species exist and to better understand the biodiversity in their area. My research is used toward a more comprehensive study of the subtribe and genus.

Залежність урожайності суцвіть ромашки лікарської від тривалості вегетаційного періоду культури

Залежність урожайності суцвіть ромашки лікарської від тривалості вегетаційного періоду культури

Weed-competitive ability of a hybrid and an inbred rice cultivar in managing Ischaemum rugosum in dry-seeded rice

Ischaemum rugosum Salisb. commonly known as ribbed murainagrass is a problematic herbicide-resistant weed in directseeded rice systems. To evaluate the competitive ability of rice cultivars against I. rugosum, a study was established with two rice cultivars (Mestiso 21, a hybrid and IR 64, an inbred). These cultivars were sown at density of 4 plants per pot with four different densities of I. rugosum (0, 2, 4, and 8 plants pot(-1)). Across weed density levels, IR 64 had 14% lower while Mestiso 21 had 20% higher plant height than I. rugosum. In competition with eight I. rugosum plants per pot, Mestiso 21 had 17% higher plant height (85 cm) than of IR 64 (73 cm). Without competition, IR 64 had higher tiller number, leaf number, leaf area, and root biomass than Mestiso 21 while in competition with eight weed plants per pot, Mestiso 21 had higher leaf biomass (29%), stem biomass (13%), specific stem length (38%), panicle biomass (29%), florets number (41%), and florets biomass (36%) than IR 64. In comparison with control (no weed competition), weed densities of 2, 4, and 8 plants pot(-1) reduced the total rice biomasses and grain yields by 32, 42, and 50%; and 26, 46, and 56% for IR 64 and by 23, 37, and 45%; and 20, 28, and 42% for Mestiso 21, respectively. The Mestiso 21 reduced the I. rugosum plant height, number of tillers, leaf biomass, inflorescence biomass, root biomass, and total aboveground biomass by 16.3, 0.3, 22.1, 31.3, 21.8, and 22.7%, respectively, compared with IR 64. The results of this study suggest that the hybrid rice Mestiso 21 has a better competitive ability to suppress I. rugosum than IR 64 therefore can be used in an integrated weed management of problematic weeds in direct-seeded rice systems.

Brachystelma vemanae (Apocynaceae–Asclepiadoideae), a new species with completely reflexed corolla lobes and solitary flowers from Eastern Ghats, Andhra Pradesh, India

Brachystelma vemanae, a new species of Apocynaceae, is described and illustrated. The relationships of new species to other known taxa of the genus from India are discussed.

One for all and all for one: retention of colour-unchanged old flowers increases pollinator attraction in a hermaphroditic plant.

Long-lived flowers increase pollen transfer rates, but these entail high water and carbon maintenance costs. The retention of pollinated and reward-free old flowers enhances pollinator visitation to young receptive flowers by increasing floral display size. This mechanism is associated with acropetal inflorescences or changes in flower colour and openness, but the retention of unchanging solitary flowers remains overlooked. We examined pollination-dependent variation in floral longevity and determined stigmatic receptivity, pollen viability and pollen removal rates among flower ages in Kielmeyera regalis, a Neotropical savanna shrub. We also evaluated the effects of floral display size on pollinator visitation rates. Lastly, we determined whether old flowers are unvisited and exclusively increase pollinator attraction to young flowers through flower removal experiments. Regardless of pollination treatment, flowers lasted fully open with no detectable physical changes for 3days. Over time, stigmas remained receptive but >95% of pollen was removed. Pollinator visitation significantly increased with floral display size and intermediate percentages (15-30%) of newly opened flowers. Accordingly, the retention of reward-free and unvisited old flowers increased young flower-pollinator interaction. Our results reveal the importance of a prolonged floral longevity in increasing pollinator attraction toward newly opened receptive flowers without changes in flower colour and form. We conclude that the retention of pollinated, reward-free and unvisited colour-unchanged old flowers in K. regalis is a strategy that counteracts the water use costs associated with the maintenance of large flowers with increased mate opportunities in a pollen-limited scenario.

Fritzschia rupestris (Melastomataceae: Marcetieae): A New Endangered Species from the Cadeia do Espinhaço, Minas Gerais, Brazil

A new species of Fritzschia is described and compared with its probable relatives. Fritzschia rupestris is characterized by its sprawling habit with elongate internodes, absence of trichomes on vegetative and floral organs, ovate to subcordate glutinous leaf blades with serrulate margins, solitary pedunculate flowers, magenta petals, dimorphic stamens with well-developed staminal appendages, calyx lobes that become thicker in fruit, and ovary apex with a few scattered sessile glands. Diagnostic line drawings, field images, SEM photos of seeds, a distribution map, and a conservation assessment are provided, along with a key to all the species currently recognized in the genus Fritzschia.

Prosopanche panguanensis (Aristolochiaceae), a new species from central Peru

Prosopanche panguanensis, from the Peruvian lowland rain forest, is proposed as a new species. The species is similar to Prosopanche costaricensis but differs with solitary flowers (vs. flowers in fascicles), a perigonial tube prolonged above the insertion point of the synandrium (vs. perigonial tube not prolonged), and staminodes cucullate and sessile (vs. bilobed in the apex). A description, illustrations, pictures of live specimens, and information about its habitat and distribution are given. An account on Prosopanche specimens recorded from Peru and their identity is also provided.

PHYSIOLOGICAL DEVELOPMENT OF HELICONIAS DERIVED FROM IN VITRO CULTURE OF ZYGOTIC EMBRYOS AND CONVENTIONAL PROPAGATION

The aim of the current study is to compare the physiological development of Heliconia bihai (L.) L. Lobster Claw Two plants derived from in vitro culture of zygotic embryos and conventional propagation. Heliconias obtained from rhizomes and from in vitro multiplication were evaluated every 30 days for ten months under greenhouse conditions. The experimental design was completely randomized (CRD), with ten repetitions, and the 2x10 factorial arrangement consisted of two plant multiplication methods and ten evaluations performed at different times. The analyzed biometric parameters were plant height, number of leaves, number of tillers, leaf area, and color intensity in the bracts. The plants derived from in vitro culture showed significant differences in the development of the evaluated physiological parameters in comparison to the plants derived from rhizomes, and they also showed early flowering. Although the in vitro culture plants derived from zygotic embryos, no morphological changes were found in the vegetative and reproductive parts (inflorescence) of the plants or in the colorimetry. It shows that the in vitro culture of zygotic embryos may be used as a technique to produce seedlings on a large-scale, thus allowing the floriculture sector to grow in the region and all over the country.

Diversification of inflorescence types in Portulaca (Portulacaceae) and its systematic implications

Portulaca is the only genus in Portulacaceae and includes ca. 100 species with worldwide distribution. Inflorescence types in Portulaca have been used as an important character in infrageneric classifications and it has been suggested that capitula and solitary flowers derive from a cyme. The present paper focuses on the study of the diversification patterns of the inflorescence within Portulacaceae based on a phylogenetic approach. A phylogenetic framework was used to estimate the ancestral inflorescence type under parsimony and maximum likelihood criteria. The results, although ambiguous, suggest that a cymose inflorescence may have been the ancestral type for Cactineae. Diversification patterns within Portulacaceae are not clear, but it is plausible that capitula and solitary flowers are derived from a cymose inflorescence. In addition, the first two types may have evolved independently at least twice in the group. These results show that the inflorescence type has limited systematic utility, contrary to the current accepted infrageneric classifications of Portulaca, and only characterizes a group of Australian species with cymose inflorescences.

Potentiometric determination of integral antioxidant activity of inflorescences of Matricaria Recutita plants cultivated under different conditions with applying growth biostimulants

У статті наведено результати досліджень впливу біостимуляторів росту «Вермибіомаг», «Вермийодіс» та «Вермистим» на антиоксидантну активність суцвіть водних та спиртових екстрактів рослин Matricaria recutita L. cорту «Перлина Лісостепу», вирощених на дерново-підзолистому ґрунті зони Передкарпаття та темно-сірому опідзоленому середньосуглинковому ґрунті зони Західного Лісостепу. Матеріалом для дослідження були суцвіття рослин M. recutita, зібрані із різних дослідних ділянок та висушені до повітряно-сухого стану. Водні та спиртові екстракти суцвіть M. recutita готували відповідно до вимог Державної Фармакопеї України. Визначення антиоксидантної активності проведено модифікованим у наших дослідженнях потенціометричним методом за допомогою медіаторної системи (0,01 МК3[Fe(CN)6] і0,0001 МК4[Fe(CN)6] в0,066 Мфосфатному буфері з pH 7,2), на основі методів Брайніної і співроб. та Аронбаєва і співроб. З'ясовано, що водні та спиртові екстракти суцвіть рослин M. recutita виявляють антиоксидантну активність. Спиртові екстракти суцвіть рослин M. recutita характеризуються вищою антиоксидантною активністю у 1,3–1,5 разів, порівняно із водними екстрактами. Встановлено, що екстракти суцвіть рослин M. recutita, культивованих в умовах Передкарпаття за внесення біостимуляторів росту характеризуються вищою інтегральною антиоксидантною активністю, порівняно із рослинами контрольного варіанту (14,36 – у водних та 20,52 мг АК / г абс. сухої маси – у спиртових екстрактах). Найвища антиоксидантна активність зафіксована у рослин, вирощених за дії «Вермибіомагу» (на 25,4 % – у водних та 26,7 % – у спиртових екстрактах порівняно з контролем. Показано, що суцвіття рослин M. recutita, культивованих в умовах Західного Лісостепу характеризуються достовірно вищою (р≤0,05) інтегральною антиоксидантною активністю на 16 %, ніж рослини, вирощені у зоні Передкарпаття

Towards a Revision of Diastema within Central America

Diastema is a genus of flowering plants within the subtribe Gloxiniinae (Gesneriaceae). Some of the key characteristics of Diastema are a racemose flowering axis consisting of solitary flowers in the axils of bracts on the stems with condensed internodes, nectary consisting of 5 finger-like glands, and a distinctive bi-lobed stigma. There are currently only twenty described species and there has been very little research performed on the genus. I am currently collecting morphological and molecular data to delineate species. Any new potential new species are then compared to the appropriate type specimens to determine circumscription. Morphological studies focus on taxonomically useful vegetative and reproductive characters with special emphasis given to trichome structure and fruit shape. Molecular studies are focused on nuclear and chloroplast genes to ascertain if any hybridization has occured. The outcomes of this research will provide a baseline for conservation and governmental agencies to work from to protect the habitat where these species exist. My research will be used toward a more comprehensive study of the subtribe and genus.

Synopsis of the spurred species of Lobelia section Stenotium (Campanulaceae) in Sierra Madre Occidental, Mexico, and the description of two new species

The genus Lobelia is cosmopolitan and comprises 423 species in 18 sections. Lobelia sect. Stenotium is the most diverse group with 153 species, has a wide distribution in continental North America and is segregated into two subgroups based on the presence of spurred flowers. There are 16 spurred Lobelia species that occur in streamside or seep areas, throughout pine and oak mixed forests from USA to Costa Rica, but they are frequent along the Pacific slopes of the Sierra Madre Occidental (SMO), Mexico, where 10 species grow. In this paper we present a synopsis of the spurred species of Lobelia in the SMO and propose two new taxa. First, Lobelia rzedowskii is morphologically similar to L. ayersiae, L. cordifolia and L. endlichii but differs by its rosulate leaves, blades 0.5–1.5 × 0.4–1 cm, subsessile, racemose to paniculate inflorescences, with (4–)10–35(–191) flowers, flowers 4–6 mm long including hypanthium, spur 0.5–1 × 0.5–0.8 mm, with the lower two calyx lobes positioned at the middle portion of the spur, white corolla with a yellow spot above lobe sinuses on the throat and staminal tube 1.3–2.5 mm long. Second, Lobelia saturnini is morphologically similar to L. knoblochii, L. macrocentron, L. mcvaughii and L. villaregalis, but differs from them by leaves (2–)4–14(–17) mm long, petioles 2–6(–17) mm long, solitary flowers, flowers 12–16 mm long including hypanthium, hypanthium 1.2–2.5 mm long, spur 2–3 mm long, pedicels (1.3–)2–9(–12) cm long and anthers 1–2.2 mm long. We include an identification key for spurred species of Lobelia in the SMO, photographs, distribution notes with a map, and illustrations.

Vegetative and reproductive growth behaviour of Xanthostemon chrysanthus (F. Muell.) Benth.-An ornamental tree in Malaysia

A study was conducted to investigate the duration of growth stages and flowering behaviour of a landscape tree, Xanthostemon chrysanthus (F. Muell.) Benth. This species is known as golden penda and locally known as jambu kuning. It is widely planted for urban beautification due to its distinctive coloured flowers. Under local climate condition, this species flowers throughout the year. However, the flowering of this species has not been studied extensively. In the present study, the growth of selected trees aged approximately six years after planting was monitored for a year. The growth duration was determined using the extended Biologishe Bundesanstalt, Bundessortenamt and Chemical Industry (BBCH) scale. Percentages of flower and fruit and new leaf abundances were expressed as estimated percentage of each stage as compared to total surface area of the tree crown. The vegetative and reproductive stages of the species required 198 and 176 days, respectively. The flowering period took about 40 days from inflorescence bud swelling to drying and senescence of stamens and petals. Unsynchronized flowering was observed among the trees. The occurrence of flowers was also influenced by the development of new leaves or fruits. The information on the duration of each growth stage and the flowering behaviour of the species may enhance a more detailed study related to flowering of urban trees in Malaysia.