Xeromorphic Adaptations Research Articles

Leaf micromorphology in Rosaceae tribe Spiraeeae (subfamily Amygdaloideae) and its systematic and ecological implications

Abstract We conducted a comparative micromorphological study on the leaves of all nine genera of the Rosaceae tribe Spiraeeae, including the monotypic Korean genus Pentactina. Spiraeeae possess amphistomatic and hypostomatic leaves. Leaf epidermal characteristics varied with the morphology of stomatal complexes, epidermal cells, trichomes, and epicuticular waxes. Specific leaf epidermal features may be systematically relevant for identifying lower taxonomic levels, genera, and/or species. For example, papillate epidermal cell types were consistently observed in Spiraea sect. Calospira. Hirtellous trichomes are diagnostic characteristics of the genera Holodiscus and Kelseya among this tribe. Short-stalked capitate glandular and crispate villous trichomes were only observed in Holodiscus microphyllus and Spiraea douglasii, respectively. We also confirmed that leaf epidermal characteristics strongly support the independent taxonomic position of the Korean endemic Pentactina and the transfer from Physocarpus to Spiraea of Physocarpus insularis. Moreover, we identified xeromorphic features in the studied taxa and inferred their ecological functions, such as water repellence and anti-transpirant activities. This study presents new perspectives for future research on character evolution and xeromorphic adaptation on the basis of leaf epidermal characteristics.

Comparative anatomical and morphological study of vegetative organs of Gymnospermium altaicum (Pall.) Spach from natural populations

Plants growing in arid environments developed structural adaptations to reduce water loss and dissipate excessive light energy. However, such adaptations as thick cuticle, sunken stomata, developed mechanical tissue, and trichomes, may have various functions and can also be found in plants growing in mesic environments. To better understand the role of xeromorphic adaptations, it is important to study plants of the same species from different habitats. The object of our study was Gymnospermium altaicum (Pall.), a small perennial plant having the status of a rare species for Kazakhstan. For anatomical and morphometric studies, plants were sampled from three populations with different moisture regimes. Populations 1 and 3 were growing in drier conditions, on south-east and north-east slopes, respectively, while population 2 was found on a north-facing slope receiving more rainfall. We demonstrate, for the first time, that anatomical features and morphometric parameters of G. altaicum are correlated to the humidity variations. The xeromorphic features of vegetative organs of plants from populations 1 and 3 were not observed in plants from population 2. The outcomes of this research will help us to better understand the adaptive potential of G. altaicum and develop effective conservation strategies for its wild populations.

Amber and plants from the Upper Cretaceous of La Gripperie-Saint-Symphorien (Charente-Maritime, Western France)

Amber and plant remains were discovered in the lower Cenomanian lignitic clay from La Gripperie-Saint-Symphorien (Charente-Maritime, western France). The amber mainly consists of scarce and infracentimetric pieces showing a wide range of sizes and colours. The shape of the amber grains greatly varies, including more or less cylindrical fragments of flows and spherical drops. Plants consist of foliar remains corresponding to isolated pinnae and pinnules of ferns (Matonia sp., Weichselia reticulata (Stokes & Webb, 1824) Fontaine emend. Alvin, 1971), leafy axes of conifers (Geinitzia reichenbachii (Geinitz, 1842) Hollick & Jeffrey, 1909, Pagiophyllum sp.) and leaves of angiosperms (including cf. Eucalyptolaurus depreii Coiffard, B.Gomez, Thiébaut & J.Kvaček and three morphotypes of undeterminable leaves). They are preserved as isolated cuticles, charcoalified compressions without cuticle, and external casts. Angiosperms are clearly the most abundant and diverse remains of the plant assemblage. This latter contrasts with most of Albian-Cenomanian coastal floras from the Aquitaine Basin, which are dominated by gymnosperms characterised by xeromorphic adaptations and tolerating halophytic conditions. Similar to the coeval sites of Puy-Puy (Charente-Maritime) and Jaunay-Clan (Vienne), the plant-rich clay from La Gripperie-Saint-Symphorien was probably deposited in innermost coastal environments heavily influenced by inland/continental freshwater.

Past climates and plant migration – the significance of the fossil record

This article is a Commentary on Denk et al. (2023), 238: 2668–2684.

SEM observations on the vegetative plant parts of Acantholimon riyatguelii Yıldırım (Plumbaginaceae), a local endemic restricted to gypsum habitats

Acantholimon riyatguelii Yıldırım is a local endemic restricted to gypsum habitats. SEM observation on roots, stems and leaves of A. riyatguelii presented detailed information of ultrastructural properties which described this species adaptations to specific conditions of gypsum habitats. This study showed that A. riyatguelii leaves which are amphistomatic exhibited strong xeromorphic adaptations reflecting numerous stomata, surface hairs, thick cuticle (∼10 µm) and advanced palisade. The xeromorphic stomata in the leaves of the A. riyatguelii growing in aridty areas are in the form of deep cavities under the epidermis. Mesophyll cells had a somewhat rounded shape and placed rather regularly in the mesophyll. Some crystal deposits were observed at stomata and inside the mesophyll cells. In the root, xylem was in the form of pentarch along with the phloem observed among the protoxylems and the periderm was ca. 100 µm thick. In the stem, the centre of the stem was filled with large xylem vessels and five bundles of phloem tissue distributed around the xylem. The ultrastructural properties of A. riyatguelii, a gypsophyte species, were given for the first time in this study at Turkey and revealed detailed descriptive ultrastructures which could serve as a source of information and reference. Finally, this study offers new and interesting avenues to interpret ultrastructural features that allow gypsophiles to tolerate drought and atypical mineral soils.

Synseeds for Propagation and Preservation of Ferocactus peninsulae (Cactaceae) and Xeromorphic Adaptations of Seedlings

Ferocactus peninsulae (A.A.Weber) Britton & Rose (Cactaceae) has great potential for commercial exploitation by the horticulture industry. It is difficult to propagate vegetatively, and we investigated novel propagation methods. The objectives were to optimize the organic supplements in nutrient medium for seed germination, synthetic seed (synseeds) production, and in vitro and ex vitro retrieval of plantlets after 12 months of cold storage. Seeds were germinated on different strengths of Murashige and Skoog's (MS) nutrient media under variable temperatures. Full strength MS medium augmented with 2.0 mg L-1 6-benzylaminopu-rine (BAP) incubated at 24°C temperature was optimum for seed germination with 98% maximum response. Synseeds were produced from the eight-week-old in vitro germinated seedlings using 2% sodium alginate and 100 mM calcium chloride solutions. These were cold stored under low temperature (- 4°C) for 12 months. The highest percentage (92%) of synseed germination and seedling growth (4.2 cm shoot with 7.1 cm root) was attained on MS medium fortified with 1.0 mg L-1 BAP after 12 wk. About 80.5% of cold stored synseeds germinated under greenhouse conditions (ex vitro) on Soilrite® with healthy shoots (3.7 cm length) and well-developed roots (4.0 cm) within 12 wk. No apparent differences were observed between in vitro and ex vitro raised seedlings. These results would reveal the short-term cold preservation of germplasm of barrel cactus, and it is also effective in in vitro and ex vitro germination. A comparative micro-morpho-anatomical study of in vitro and acclimatized seedlings of F. peninsulae was conducted to understand the xeromorphic adaptations of cacti with reference to stomata, spines and internal anatomy peculiar to the arid environments.

Structural, physiological and genetic diversification of Silene vulgaris ecotypes from heavy metal-contaminated areas and their synchronous in vitro cultivation

Main conclusionResults provide significant comparison of leaf anatomy, pigment content, antioxidant response and phenolic profile between individuals from miscellaneous populations and describe unified cultivation protocols for further research on stress biology.The plant communities growing on heavy metal-polluted areas have attracted considerable attention due to their unique ability to tolerate enormous amounts of toxic ions. Three ecotypes of Silene vulgaris representing calamine (CAL), serpentine (SER) and non-metallicolous (NM) populations were evaluated to reveal specific adaptation traits to harsh environment. CAL leaves presented a distinct anatomical pattern compared to leaves of SER and NM plants, pointing to their xeromorphic adaptation. These differences were accompanied by divergent accumulation and composition of photosynthetic pigments as well as antioxidant enzyme activity. In CAL ecotype, the mechanism of reactive oxygen species scavenging is based on the joint action of superoxide dismutase and catalase, but in SER ecotype on superoxide dismutase and guaiacol-type peroxidase. On the contrary, the concentration of phenylpropanoids and flavonols in the ecotypes was unchanged, implying the existence of similar pathways of their synthesis/degradation functioning in CAL and SER populations. The tested specimens showed genetic variation (atpA/MspI marker). Based on diversification of S. vulgaris populations, we focused on the elaboration of similar in vitro conditions for synchronous cultivation of various ecotypes. The most balanced shoot culture growth was obtained on MS medium containing 0.1 mg l−1 NAA and 0.25 mg l−1 BA, while the most abundant callogenesis was observed on MS medium enriched with 0.5 mg l−1 NAA and 5.0 mg l−1 BA. For the first time, unified in vitro protocols were described for metallophytes providing the opportunity to conduct basic and applied research on stress biology and tolerance mechanisms under freely controlled conditions.

Structural and anatomical peculiarities of leaf blade of the genus Begonia L. (Begoniaceae C. Agardh) species

The aim – to study anatomical structure of leaf blade of the genus Begonia L. species and its connection with the peculiarities of habitats in which plants occur in nature. Material and Methods. The study was conducted with 8 species of the genus Begonia, which grow in the glasshouses of the M.M. Gryshko National Botanical Garden of the NAS of Ukraine. Normally developed leaves of the middle formation were taken as samples. In order to make photos of epidermal and mesophyll cells slices and biometric researches light microscope equipped with a digital camera was used. Measurements were performed using licensed programs Axio Vision Rel. 4.7 (Carl Zeiss, Jena, Germany). Results. The most mesophyllous species are B. dichotoma and B. dregei, the least mesophyllous – B. mollicaulis and B. venosa. Only in B. subvillosa prevalence of palisade parenchyma was found. In contrast to all other studied species, B. subvillosa grows in open areas. In other species domination of spongy parenchyma was established. The presence of hypoderm in B. venosa leaf blade and large epidermal cells in other model species is an adaptation to adverse conditions especially the lack of moisture. Conclusions. Prevalence of spongy parenchyma in leaf blades of studied species indicates “shadow” mesophyll structure that allows them to grow in terms of shading. Xeromorphic adaptations of the genus Begonia species include the presence of large elongated epidermal cells and hypoderm. An important role in reducing the evaporation intensity from the leaf surface plays cuticle and trichomes.

Effect of drought on morphological and functional traits of Poa ligularis and Pappostipa speciosa, native perennial grasses with wide distribution in Patagonian rangelands, Argentina

Poa ligularis Nees. Ap. Steudel and Pappostipa speciosa (Trin. et Rupr.) Romaschenko are dominant perennial grasses in the arid Patagonian rangelands of Argentina. Both species are exposed to periods of water shortage during spring-summer and are grazed by domestic and native herbivores. Pappostipa speciosa displays xeromorphic adaptations and is less preferred by herbivores than P. ligularis. The knowledge of how drought affects morphological/functional traits in coexisting perennial grass species is useful to understanding the function of desert perennial grasses, and for the use and conservation of Patagonian arid rangelands. The hypothesis of this study was that co-existing perennial grasses contrasting in drought resistance mechanisms display different degrees of phenotypic plasticity in underlying and/or functional traits. Plants of both species were exposed to two levels of gravimetric soil moisture: 16% (~field capacity) and 4%. Plant vegetative and reproductive traits were measured weekly in individual plants and these were harvested at the end of the experiment. Aboveground and root biomass were separated in the harvested plants and the concentration of photosynthetic pigments was assessed in green leaves. The trait response range was also calculated through the plasticity index. In both species, drought stress led to significant reductions in plant height, total plant dry weight, number of total leaves, dry weight of green and senescent leaf, percentage of flowering plants, length of inflorescences, and number, length and dry weight of roots. The concentration of photosynthetic pigments increased under drought in both species. In conclusion, drought strongly affected reproductive and vegetative traits in both species and the greatest negative effect of drought was found in P. speciosa, the most conservative species. However, our findings might indicate that both species are able to maintain photosynthetic activity through the increase of photosynthetic pigments under drought conditions in Patagonian rangelands.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF MACADAMIA (MACADAMIA SPP.): A REVIEW

SUMMARYThe macadamia nut is the only commercial food crop indigenous to Australia. It originated along the fringes of rainforests, only becoming an important internationally traded crop in the late 20th century. Australia is now the main centre of production, following a lead set by Hawai'i. The crop is also important in Central America and southern Africa. The majority of recent research reported in the literature on the physiology and water relations of macadamia has been undertaken in Australia. Macadamia is a tall evergreen tree in which vegetative growth occurs in a series of flushes. Mild water stress suppresses growth, but compensatory growth occurs on re-watering. Flowers form on hardened wood within the leaf canopy. Floral initiation occurs in late autumn, with flowering in the following spring. Flowering is profuse but only 5–10% of the flowers set fruit and less than 1% of the flowers reach maturity as fruits due largely to premature abscission. High temperatures (>30 °C) can contribute to the shedding of fruit. It takes about 12 months from floral initiation to the completion of harvest. Macadamia root systems are described as relatively shallow and spreading. The taproot can extend to depths of >1.2 m, with a dense matt of fibrous roots in the top 0.4 m. Proteoid rootlets are also present. Stomata are only found on the abaxial surface of the leaf. Macadamia has several attributes that help to explain its apparent tolerance to periodic dry conditions as found in its native habitat. These include leaves with xeromorphic adaptations, stomatal closure without concurrent changes in leaf water potential and an efficient water transport system. There has only been one serious attempt to measure the actual water use of macadamia. Most irrigation experiments have been poorly planned and/or the outcomes were inconclusive. Nut yields are cyclical and highly variable, making it difficult to establish cause and effect. It is not yet possible to say with evidence where and when irrigation is worthwhile.

Ecological adaptations of Hypocyrta glabra Hook. flowers

The research on the blooming ecology and the flower morphology of <i>Hypocyrta glabra</i> Hook. (Gesneriaceae) cultivated in laboratories and outdoors have been carried out. The life span of flowers and morphological changes in successive phases of the blooming period have been observed. The <i>H. glabra</i> flowers are protandrous and the stamens translocate during the flowering process. The macro- and microstructure of calyx, corolla, androecium, gynoecium and nectaries have been analyzed. The size, shape and viability of pollen grains have been designated and their number per stamen head has been calculated. The location of nectaries in <i>H. glabra</i> flowers has suggested that they stem from the 5<sup>th</sup> stamen during phylogenesis. It has been proved that the nectaries are provided by numerous vascular bundles and that the nectar is secreted by stomata. The stomatal field comprises 2/5 of nectary height and is situated on the abaxial side of the apix part. The average number of stomata is 63.2 per 1 mm<sup>2</sup>. The average amount of nectar produced by 10 flowers in their fourth day of life reached 223.7 mg. The sugar concentration was 32.7%. Numerous glandular and non-glandular trichomes have been noticed on the surface of calyx, corolla and gynoecium, which indicate the xeromorphic adaptation of the flower. It has been observed that the numbers of glandular and non-glandular trichomes per unit of the external surface of corolla are similar. Outdoors the secretion produced by calyx and corolla glands was willingly collected by wasps. It seems that such features of <i>H. glabra</i> flowers as position, shape and colour of corolla, the abundance of the nectar and pollen produced are connected with their adaptation to pollination by humming-birds in the species natural environment.

Ontogeny of the mucilage ducts of Polygala angulata DC. (Polygalaceae)1

Abstract The present study describes the occurrence of mucilage ducts within Polygalaceae. Polygala angulata DC. is a species from the Brazilian cerrado that possesses secretory ducts in the stem angles of primary growth. First, a schizogeneous process and later, a lytic process both take place in the course of secretory duct formation, characterizing the development of the glands as schizolysigenous. Histochemical tests confirm the mucilage nature of the exudate. The presumable functions of this gland are associated with xeromorphic adaptation of this species to the cerrado environment.

A Study on Tribulus Terrestris L. Anatomy and Ecological Adaptation

ABSTRACTA study on Tribulus terrestris root, stem and leaf anatomy in implication for its ecological adaptation was conducted. The anatomical structure of the leaf showed clearly distinguished xeromorphic adaptations typical for C4 plants. The lamina is isobilateral and amphistomatous and possesses thick cuticle, “Kranz” anatomical structure, mesophyll with reduced intercellular spaces, epidermis with small stomata and reduced stomatal density and numerous unicellular trichomes particularly on the lower epidermis. The leaf structure explains the plant's poor performance when shaded and limits its distribution to sunny locations. The stem and root have compact structure with well developed vascular tissue, high sclerification and little parenchyma. The small intercellular spaces make roots and stems not well aerated and explain the poor growth of Tribulus terrestris plants on waterlogged soils.

Analysis of anatomical and micromorphological characteristics of Iva xanthifolia nutt.

Iva xanthifolia is a North American weed species, which was introduced and naturalized in Europe. Anatomical and micromorphological characteristics of this species were investigated, in order to get better knowledge of its biology, which could help in development of strategies for prevention of its spreading. Detailed descriptions of lamina, petiole, stem and inflorescence axis anatomical structures were given, together with micromorphological characteristics of epidermis and indumentum of lamina, petiole, stem, inflorescence axis, involucre and fruit. All vegetative organs had mesomorphic structure, with some xeromorphic adaptations. Mechanical tissue was well developed, which gave those plants additional strength and resistance. Trichomes were the most numerous on lamina and in the region of inflorescence, while rare on petiole and stem epidermis and their distribution varied according to plant organ.

Early Responses to Acute Ozone Exposure in Two Fagus Sylvatica Clones Differing in Xeromorphic Adaptations: Photosynthetic and Stomatal Processes, Membrane and Epicuticular Characteristics

Two Fagus sylvatica L. clones were used to investigate the early responses to acute O3 exposure (150 nL L(-1), i.e., 1.35x ambient hourly peak in rural Italy) and whether xeromorphic adaptations affect gas exchange, membrane, and epicuticular responses. One clone originated in a wet and temperate climate in Central Italy (Tuscany); the other clone originated in a warmer and drier climate in the southern-most part of the F. sylvatica distribution (Sicily). Because of higher base gas exchange rates, the most negative effects of O3 exposure (gas exchange impairment, uncoupling between net photosynthesis and stomatal conductance, increased membrane lipid peroxidation) were found in the southern clone. Xeromorphic adaptations (higher epicuticular waxes and stomatal density, lower leaf wettability and size) were found in this clone. Our results suggest that xeromorphism may increase O3 sensitivity in species not adapted to face water stress, like the mesophilic F. sylvatica, when experiments are carried out with full irrigation. We present evidence describing the relationship between gas exchange and number and status of stomata. Stomatal density and the structural damage to stomata resulting from O3 exposure did not affect gas exchange: In fact, non-stomatal limitations to photosynthesis prevailed over stomatal limitations.

Xeromorphic adaptations of some Mesozoic gymnosperms. A review with palaeoclimatological implications

Plant cuticles have proved to be a high-resolution proxy of palaeo- p CO 2 variation. Mesozoic gymnosperms, however, show a wider range of xeromorphic adaptations than their living relatives, and these may explain stomatal density/stomatal index differences between taxa within the same fossil assemblage. Four main adaptive responses to water loss are pointed out: reduction of solar radiation, reduction of drought-air circulation, reduction of evapotranspiration, and trapping of surface external water. In conclusion, we recommend supplementing quantitative estimates of stomatal density and index by qualitative observations of cuticular adaptive macro- and microstructures. To cite this article: F. Thévenard et al., C. R. Palevol 4 (2005) .

The adaptation of Silene vulgaris to growth on a calamine waste heap (S. Poland)

Two populations of Silene vulgaris (Moench) Garcke (= S. inflata Mill.= S. cucubalus (L.) Wib.) were cultivated and compared. One population was from a calamine waste heap in Bolesław near Olkusz in southern Poland, the other a normal population from the Botanical Gardens in Warsaw. In comparison with the normal population, the plants from the waste heap population were characterized by faster growth, thicker and narrower leaves, and trailing shoots of small diameters. The xeromorphic adaptations of the waste heap population were accompanied by increased water stress resistance (PEG 6000 test). The main life strategy (type r) of the calamine waste heap population, associated with growth under the difficult conditions of the place, is based on accelerated growth and rapid entry into the generative phase. The smaller biomass gain of these plants is compensated for by abundant flowering (by 23%). Moreover, these plants exhibit a very high tolerance to lead. Tests with PbCl 2 showed that lead stimulated root elongation (up to 164% of controls), biomass gain of roots, and formation of root hairs.

Ecological patterns in theBromeliaceae of the lomas formations of Coastal Chile and Peru

Studies of geographic distribution and physiological adaptations in theBromeliaceae of coastal Chile and Peru provide insights into the ecological patterns of habit selection and speciation. The hyperarid coastal Atacama and Peruvian Deserts along the Pacific coast of South America contain a surprisingly rich flora of bromeliad species. These include representatives of all threeBromeliaceae subfamilies: two terrestrialBromelioideae and two terrestialPitcairnioideae, all with rooted growth morphologies, and 14 species ofTillandsioideae (allTillandsia) with epiphytic and unrooted, terrestraial representatives. TheBromelioideae are represented by two species ofPuyaMolina, one each in Peru and Chile. ThePitcairnioideae are represented by two genera,Deuterocohnia andPitcairnia, with one species each. The 14Tillandsia species are distributed in five subgenera which have successfully invaded the coastal deserts, and include both widespread and local endemics with xeromorphic adaptations. All theTillandsia species are epiphytic in the broad sense, but in addition to growing on plants, they are found growing on rocks (i.e. saxicolous or epilithic). Six species (T. purpurea, T. latifolia, T. capillaris, T. marconae, T. werdermanii, andT. landbeckii) have evolved a highly specialized substrate ecology where they grow essentially unrooted on sand (i.e. epiarenic). Nowhere in the world are bromeliads more dominant or have more biomass than in these coastal species growing on sand. Many of these species grow at the absolute limits of vascular plant tolerance, with the entire community consisting of a singleTillandsia species. Rooted, terrestrial bromeliads in the coastal lomas formations (allPitcairnioideae) include CAM, C3, and C3-CAM flexible taxa in their metabolic systems, the CAM species growing in the most arid sites along the coast and C3 species growing in the most mesic habitats within the center of the coastal fog belt where fog moisture input is highest. All of the epiphyticTillandsia species of the coastal desert region utilize CAM metabolism entirely or in part. At least two species,T. latifolia andT. tragophoba, utilize a flexible C3-CAM mode of carbon fixation. Whereas most of the desert-inhabitingTillandsia species have relatively narrow leaves covered by water absorbing trichomes on their surface,T. multiflora in northern Peru andT. tragophoba in northern Chile are tank-forming species where the bases of the leaves form a water-containing reservoir. The occurrence of the latter as a local endemic in hyperarid northern Chile is remarkable since it occurs thousands of kilometers south of its closest potential relatives in the central Andes.

Sclerophylly in beech (Fagus sylvatica L.) trees: its relationship with crown transparency, nutritional status and summer drought

Sclerophylly is common in evergreen Mediterranean flora, but can also manifest itself in mesophile vegetation: in those cases it is considered an adaptation to conditions of environmental stress. Sclerophylly is the result of tissue thickening and histochemical alterations (lignification of tissues and accumulation of phenolics), and is a xeromorphic adaptation. According to Guray Kutbay and Kilinc (1994) sclerophyllous adaptations occur as a consequence of nutritional deficiencies, especially shortages of nitrogen and potassium. Such alterations can also be induced by low ozone concentrations (Gunthard-Goerg et al, 1993). It has moreover been suggested that tissue lignification is a non-specific reaction in trees subjected to stress (Vance et al, 1980; Mayo et al, 1992). The accumulation of phenolic compounds also plays an important role in the tree's resistance to adversities (Nicholson and Hammerschmidt, 1992).

The character states of the Caribbean monotypic endemic Strumpfia (Rubiaceae)

Strumpfia, restricted to littoral habitats, is characterized by ternately arranged ericoid leaves with extreme xeromorphic adaptations. The flowers, with quincuncial (imbricate s.1.) corolla lobe aestivation, have the anthers fused into a “true” anther tube. The bicarpellate gynoecium has two erect, anatropous ovules per locule. In addition to the “true” septum, the ovary also has a secondary or “false” septum, arranged at right angles to the former and only developed in the upper part of an ovary. The drupaceous fruits contain a plurilocular stone which, typically, is four‐seeded. Erroneous descriptions of Strumpfia's ovary as bilocular with one ovule per locule may have been due to the frequent presence of only two seeds in a stone (one seed per locule aborted and crushed). As opposed to the widespread protandry in the Rubiaceae, the genus shows proterogyny. In functionally female stage, the style is straight and raises the exposed stigmatic surfaces above the level of the anther tube and its apical appendages. In functionally male stage, the style contracts so that the stigmas “plug” the entrance to the anther tube; at this stage the pollen is released from the anther tube by means of apical pores. Strumpjia has a chromosome number of x=n=II (first count for the genus). The genus' systematic position has hitherto been considered to be uncertain. A comparison of its character states with other Rubiaceae, nevertheless, led to inconclusive results. Because of a) many unusual and, in part, unique features and b) the lack of detailed comparative data for neotropical Rubiaceae, the genus' subfamilial and tribal position remains obscure.