Straight Trichomes Research Articles

A New Species of Hemilophia (Brassicaceae) from China

Hemilophia sessilifolia is described and illustrated. Its relationship to the other species of Hemilophia is discussed. The genus Hemilophia Franchet consists of three species, H. pulchella Franchet, H. rockii O. E. Schulz, and the new species H. sessilifolia Al-Shehbaz, Arai & H. Ohba, all endemic to southwestern Sichuan and adjacent Yunnan, China. Hemilophia is readily distinguished from the related Chinese Dipoma Franchet by the appendaged and strongly inflated bases of the median staminal filaments, slender replum, entire leaves, and straight fruiting pedicels, and by lacking the fruit septum. Dipoma has slender filaments, strongly flattened replum, apically dentate leaves, strongly curved and loop-forming fruiting pedicels, and complete septum. Hemilophia is separated from the Himalayan and central Asian Dilophia Thomson by having slender rhizomes, appendaged and strongly inflated bases of the median staminal filaments, slender replum, and large (2-3 mm) seeds, 1 or 2 per fruit. Dilophia is a non-rhizomatous perennial with slender filaments, broadly winged replum, and small (ca. 1 mm) seeds, several per fruit. The new species, Hemilophia sessilifolia, which is known only from the type collection, was collected during a recent Sino-Japanese expedition to Dauxue Shan, Yunnan. Hemilophia sessilifolia Al-Shehbaz, Arai & H. Ohba, sp. nov. TYPE: China. Yunnan: Deqe, around Dauxue Shan, 28?34'N, 99?48'E, 4300-4550 m, 28 Aug. 1996, Wu Sugong, Hiroshi Ikeda, Michio Wakabayashi, Futoshi Miyamoto, Yang Yongping & Takao Kikuchi 953 (holotype, TI; isotypes, KUN, MO). Figure 1. Species ab H. pulchella Franchet et H. rockii O. E. Schulz foliis caulinis sessilibus, sepalis membranaceis integris facile cadentibus, petalis persistentibus, stylo glabro, et trichomatibus simplicibus obtecta bene differt. Herbs perennial, rhizomatous. Rhizomes slender, not scaly. Stems 1 to several from basal rosette or solitary from rhizomes, 3-9 cm tall, simple or fewbranched, with spreading to appressed simple trichomes 0.06-0.25 mm long. Basal leaves oblanceolate, 6-10 x 1.5-2.5 mm, dry at anthesis, densely beset with straight simple trichomes 0.81.3 mm long. Cauline leaves oblong to oblong-oblanceolate, 2.5-5(-8) x 1-2(-2.5) mm, sessile, entire, obtuse at apex, glabrous or minutely hairy as on stem. Inflorescences corymbose racemes, not elongated in fruit, bracteate throughout; bracts similar to cauline leaves. Sepals obovate, membranous, early caducous and leaving 4 receptacular teeth, not saccate, 1.8-2.7 x 1.2-1.5 mm, entire, rounded at apex. Petals persistent to fruit maturity, broadly obovate, 2-lobed, abruptly narrowed to claw, 6-7 x 4-5.5 mm, creamy white with dark green veins, pale to light brown at mouth, apical notch to 2 mm deep; claws 1.5-2.5 mm long. Filaments white; lateral filaments slender, unappendaged, 1.8-2.2 mm long; median filaments 1.9-2.5 mm long, basal half strongly inflated to form an oblong appendage 1.1-1.3 mm long; anthers green. Nectar glands surrounding base of lateral stamens, subtending base of median filaments. Fruiting pedicels slender, straight, divaricate, 5-6 mm long, pilose. Fruit oblong, dehiscent, glabrous; valves thin papery, navicular, 3-4 x 1.5-2 mm, with 3 rows of crests, 1 row on midvein and on either margin; replum slender, not flattened; septum absent; gynophore obsolete to 0.1 mm long; style glabrous, conical, 1-1.5 mm long; stigma entire. Seeds 1 or NOVON 9: 8-10. 1999. This content downloaded from 207.46.13.133 on Fri, 22 Jul 2016 03:58:59 UTC All use subject to http://about.jstor.org/terms Volume 9, Number 1 1999 Al-Shehbaz et al. Hemilophia sessilifolia from China 9

A Revision of Sisymbriopsis (Brassicaceae)

A Revision of Sisymbriopsis (Brassicaceae)

Isolation and toxicity of Cylindrospermopsis raciborskii from an ornamental lake

In Australia, the tropical/ subtropical cyanobacterium Cylindrospermopsis raciborskii forms substantial blooms in some drinking water supply reservoirs, rivers and recreational water bodies during the warmer months of the year. This paper describes the isolation, culture and toxicity characterisation of Cylindrospermopsis from a water bloom in a small lake in NSW, Australia. The cyanobacterium grew as straight trichomes terminating with a characteristic heterocyst. The toxic alkaloid cylindrospermopsin was separated and identified by high-performance liquid chromatography at a concentration of 5.5 mg/g dry cells, 0.026 pg/cell. Intraperitoneal injection of sonicated cells caused liver, kidney, intestinal and lung damage, with an ld 50 of 52 mg cells/kg mouse body weight at 24 hr, and 32 mg/kg at 7 days. The 24 hr mouse toxicity is not consistent with previous studies using pure cylindrospermopsin, and is suggestive of other toxic compounds in this isolate.

Profile of a bloom of the cyanobacterium Cylindrospermopsis raciborskii (Woloszynska) Seenaya and Subba Raju in the Fitzroy River in tropical Central Queensland

The physical, chemical and biotic conditions before and during a bloom of predominantly coiled heterocystous C. raciborskii are described. Initial increases in the population of this species were associated with windy days and the first downward movement of the thermocline into an anoxic hypolimnion after an extended period of stable stratification and no flow. Exponential growth and bloom formation coincided with the amval and retention of first wet-season inflows into the river impoundment. Cyanobacteria and rotifers dominated the planktonic assemblage and chytrids (cyanobacterial pathogens) were present when the cell density of cyanobacteria peaked. Grazing of the coiled forms that dominated during the bloom was not recorded, but the rotifer Brachionus angularis has been observed ingesting entire straight trichomes of C. raciborskii.

Interaction of bean leaf pubescence with rust urediniospore deposition and subsequent infection density

SummaryThe role of dense straight trichomes on bean leaves associated with race‐nonspecific resistance to rust was studied using a settling tower method for uniform inoculation. Abaxial leaf trichomes, which occur only on adult leaves, trapped significant numbers of urediniospores, especially those deposited in clusters, and resulted in reduced effective inoculum reaching the leaf surface. In the field where infection conditions are often less than optimum, leaf pubescence would partially explain the observed resistance. However, the observed increase in total number of spores as well as similar infection densities on fully expanded leaves of glabrous and pubescent genotypes cannot be explained by the trichomes. Other physical or chemical features of the leaf surface such as waxes or cations may play a role. The ecological fit of leaf pubescence is discussed.

Characterization and density of trichomes on three common bean cultivars

Trichomes have been implicated as a mechanism which can confer resistance to both plant pests and drought. A study was conducted to provide information regarding genetic variability for trichome distribution and density among three diverse dry bean (Phaseolus vulgaris L.) cultivars, and to characterize the types of trichomes present among the cultivars. Trichomes on the leaf surfaces were micrographed with a scanning electron microscope (SEM) and counted using a stereomicroscope on both the abaxial and adaxial leaf surfaces of the cultivars ‘Bill Z’, ‘Pompadour Checa’ and ‘Diacol Calima’. Straight, hooked, and glandular trichomes were observed on the leaf surfaces of each cultivar. SEM micrographs are presented for the leaf surfaces of each cultivar and trichome type. The abaxial leaf surface had more straight trichomes than the adaxial leaf surface for ‘Pompadour Checa’ and ‘Diacol Calima’, however ‘Bill Z’ had more on the adaxial surface. The opposite relationship existed among the cultivars and leaf surfaces for the hooked trichomes.

Passiflora brachyantha (Passifloraceae), a New Species from the Andes of Southern Ecuador

A new species of Passifora subg. Tacsonia is described from the Andes of southern Ecuador. Passiflora brachyantha is placed in section Bracteogama, where it most closely resembles another short-flowered species, P. glaberrima, which is endemic to Peru. Members of Passifora subg. Tacsonia (A. L. Juss.) Triana & Planchon, are tendriled lianas confined to high Andean habitats, distributed from the Cordillera de Merida in northwestern Venezuela to Bolivia. One cultivated species, Passiflora pinnatistipula Cav., is found in mesic sites in the Andes of Chile. The plants are characterized by long-tubed, highly colored, hummingbird-visited flowers, and the geographical distribution of the plants coincides with that of Ensifera ensifera, the sword-billed hummingbird (Escobar, 1980, 1989b; Schauensee, 1982). Hypanthium length in the subgenus varies, however, and falls mainly into two groups: (1) longtubed species probably pollinated by Ensifera ensifera, as is the most widespread species, Passifora mixta L. f. (Snow & Snow, 1980), and (2) shortertubed species presumably pollinated by shorter-billed hummingbirds. There are few species of intermediate hypanthium length (Escobar, 1980). Since all of the subgenera of Passifiora that are confined to the high Andes produce flowers adapted for hummingbird pollination (Escobar, 1989b, and unpublished data), it is likely that the short-tubed taxa, which are most common in southern Ecuador and northern Peru, have speciated in response to the selective pressures exerted by their pollinators. Section Bracteogama (DC.) L. Escobar comprises 14 of the 47 species placed by Escobar in subgenus Tacsonia (Escobar, 1980, 1987, 1988, 1989a) and has its center of diversity in the moist montane forests of southern Ecuador and the eastern Andean slopes of northern Peru around the Huacabamba depression. The members of the section are recognized by the presence of large, coriaceous, mostly connate bracts that enclose and presumably protect the bud during development (Escobar, 1980; Harms, 1925). Both long-flowered and short-flowNOVON 2: 198-200. 1992. ered species occur in this section. The new species described here is another short-flowered member of section Bracteogama. Passiflora brachyantha L. Escobar, sp. nov. TYPE: Ecuador. Loja: 8 km W of Loja on road to Catacocha, 7,400 ft., 30 Jan. 1979 (fl, fr), R. M. King & F. Almeda 7887 (holotype, US). Figure 1. Differt a Passiflora glaberrima (A. L. Juss.) Poiret caulibus foliis bracteisque pubescentibus, foliis majoribus apicibus acuminatis, et floribus roseis. Lianas with stout tendrils, pubescent on stems, petioles, peduncles, bracts, and abaxial surface of leaves and stipules, with straight to wavy, transparent trichomes to 0.5 mm long. Stems angulate, striate. Leaf blades 3-lobed, 3.5-7.3 cm long, 7.811.0 cm wide, parted ca. 34 their length into 3 elliptic segments, acuminate at apex of lobes, shallowly cordate at base, glandular-serrate at margins, coriaceous; lateral segments 2.2-5.5 cm long, 1.63.4 cm wide, divergent from mid-segments ca. 90?; mid-segments 3.5-7.3 cm long, 1.6-3.3 cm wide; petioles 1.2-2.7 cm long, with 3-5 subspherical nectaries 0.7-1.2 mm long, 0.8-1.0 mm wide, scatt red on upper half of adaxial surface; stipules reniform, concave, 1.2-1.5 cm long, ca. 6 mm wide, attenuate at apex, oblique at base, shallowly glandular-serrulate at margins, coriaceous, glabrous on adaxial surface. Peduncles slender, 2.7-3.4 cm long, bearing pendent flowers; bracts oblong, connate ca. 34 their length from base, forming an ampliate tube at base of hypanthium, each bract 3.1-3.5 cm long, 1.0-1.1 cm wide, acuminate at apex. Flowers 6.46.8 cm long, ca. 3.5 cm wide, bright pink; hypanthium 3.9-4.0 cm long, 0.4-0.6 cm wide (pressed), dilated at base, pubescent on outer surface with straight, transparent trichomes ca. 0.3 mm long; sepals oblong, ca. 2 cm long, ca. 0.6 cm wide, pubescent with subterminal aristae ca. 1 mm long on abaxial surface; petals subequal to sepals; corona tuberculate, ca. 0.3 mm long; ovary ellipsoidal, pubescent with fine, straight trichomes ca. 0.1 mm This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 06:16:24 UTC All use subject to http://about.jstor.org/terms Volume 2, Number 3 1992 199 Escobar Passiflora brachyantha

Geosmin and 2-Methylisoborneol Production by Cyanobacteria in Fish Ponds in the Southeastern United States

Levels of geosmin and 2-methylisoborneol and composition of phytoplankton communities were determined for water samples collected from 35 fish ponds at Auburn, Alabama, and 34 ponds in west-central Mississippi. In Auburn ponds, geosmin levels ranged from 0.05 to 8.9 µg/l but 2-methylisoborneol was never detected. Highest geosmin concentrations were measured in ponds with plankton blooms dominated by Anabaena species with straight trichomes. In Mississippi ponds, 2-methylisoborneol levels ranged from 0.05 to 76 µg/l. Highest 2-methylisoborneol concentrations were associated with blooms of Oscillatoria cf. chalybea, a cyanobacterium that produces 2-methylisoborneol in unialgal culture. Geosmin was found infrequently in Mississippi pond waters; geosmin levels ranging from 0.05 to 6.25 µg/l could be associated with blooms of Anabaena spiroides, and always concurred with 2-methylisoborneol concentrations ranging from 0.45 to 3.25 µg/l. Neither geosmin nor 2-methylisoborneol at either location could be associated with phytoplankton blooms of Aphanizomenon flos-aquae, Oscillatoria agardhii, Raphidiopsis brookii, or Microcystis aeruginosa.

Geosmin Production by Cyanobacteria (Blue‐green Algae) in Fish Ponds at Auburn, Alabama

AbstractStudies on production of geosmin, the compound responsible for earthy‐muddy flavor in water and fish, were carried out at the Auburn University Fisheries Research Station. Water was collected from ponds during 44 cyanobacterial bloom periods from April to September. Geosmin (trans‐1, 10‐dimethyl‐trans‐9‐decalol) was detected at levels averaging 4.77 μg/L when Anabaena species with straight trichomes were predominant. Lower geosmin concentrations were associated with blooms of Anabaena species with coiled trichomes, Microcystis aeruginosa, and Aphanizomenon flos‐aquae, and averaged 0.24, 0.12, and 0.07 μg/L, respectively. Study of four Anabaena blooms over a period of 4–8 weeks showed that changes in geosmin were correlated significantly with changes in trichome abundance. Geosmin disappeared from the water in seven days when Anabaena died. Comparison of geosmin concentrations in raw and filtered water showed that, on average, 90% of the geosmin could be associated with the particulate fraction. Dissolved geosmin concentrations ranged from 0.07–0.85 μg/L.

Morphological characterization of Oscillatoriales (Cyanobacteria) from Ross Island and southern Victoria Land, Antarctica

Field populations of Oscillatoriales, from fresh and saline lakes and ponds, and from terrestrial habitats, are characterised on the basis of their morphology and morphometry. Fifteen morphotypes are recognized principally from the following characteristics; cross-sectional shape of the trichome, presence or absence of a calyptra on the apical cell, occurrence or otherwise of numerous trichomes within a common sheath, and trichome width distribution. Where possible morphotypes are assigned to traditional species described by earlier investigations of algae in the Ross Sea region and a reassessment is made of the early descriptions, in some cases using material from the identical locations to the original collections. The following traditional species are described; Lyngbya murrayi, Microcoleus vaginatus, Oscillatoria deflexa, O. koettlitzi, O. priestleyi, O. sancta, Phormidium autumnale and P. subproboscidea. Intraspecific morphotypes of M. vaginatus, O. priestleyi and P. autumnale are recognised on the basis of trichome width. A new species and variety of Crinalium (Crow) Winder, Stal & Mur, a genus characterized by flattened trichomes, are described from cryoconite ponds on glaciers. C. glaciale sp. nov. possesses wide, straight trichomes in contrast to C. glaciale var. helicoides nov. var. in which trichomes are narrower and helically coiled.

Fine structural analysis of the thoracic longitudinal stripes of Zaprionus vittiger (Diptera)

The structure of the longitudinal zebra stripes on the thorax of adult Zaprionus vittiger has been investigated by light-, polarization-, transmission electron-, and scanning electron microscopy. Each stripe consists of a central white stripe of about 50 μm width and two lateral dark brown stripes about 30 μm wide. Three different types of trichomes occur: Very long bent trichomes of the grooved-type, long bent trichomes of the crested-type, and short straight trichomes. The central white stripe contains neither bristle organs nor short straight trichomes but carries many long bent trichomes most of which are of the grooved type, contain two cavities and polarize the light in the polarization microscope. The dark brown stripes carry bristle organs and many trichomes of the short and straight-type. Bent trichomes of the crested-type are found on the whole zebra stripe at about equal frequencies; they contain no cavities and do not polarize the light. The cuticle of the dark stripes is underlain by pigment cells. It is suggested that the pigment granules in the epidermal cells cause the dark color of the dark brown stripes, whereas the form and structure of the bent grooved type trichomes cause the white color of the central stripe.

Resistance of Peanuts to the Potato Leafhopper1

Abstract More than 700 peanut (Arachis hypogaea) lines from the North Carolina germplasm collection were evaluated for resistance to the potato leafhopper, Empoasca fabae Harris, from 1961 to 1972. Twelve lines were selected as being highly resistant to the potato leafhopper. The lines represent two diverse sources of germplasm resistant to the potato leafhopper. A study of the nature of resistance using standard histological techniques revealed leafhopper resistance was associated with a thick epidermis, long trichomes, and with a high percentage of straight trichomes on leaves. Leafhopper susceptible peanuts have leaves with an appressed surface texture.