White Trichomes Research Articles

Using scanning electron microscopy and molecular data to discover a new species from old herbarium collections: The case of Phlomoideshenryi (Lamiaceae, Lamioideae).

Phlomoides is one of the largest genera of Lamiaceae with approximately 150-170 species distributed mainly in Eurasia. In this study, we describe and illustrate a new species, P.henryi, which was previously misidentified as P.bracteosa, from Yunnan Province, southwest China. Molecular phylogenetic analyses revealed that P.henryi is found within a clade in which most species lack basal leaves. In this clade, the new species is morphologically distinct from P.rotata in having an obvious stem and, from the rest, by having transparent to white trichomes inside the upper corolla lip. In addition, micro-features of trichomes on the calyx and leaf epidermis can differentiate the new species from other species grouped in the same clade and a key, based on trichome morphology for these species, is provided. The findings demonstrate that the use of scanning electron microscopy can reveal inconspicuous morphological affinities amongst morphologically similar species and play an important role in the taxonomic study of the genus Phlomoides.

Two New Species and a New Record of Astragalus sect. Ammodendron (Fabaceae) from Northeastern Iran

Following study of specimens belonging to Astragalus L. sect. Ammodendron Bunge collected from northeastern Iran, two new species and a new record for Iran are described and reported. Astragalus ayatollahii Nasseh, Joharchi & F. Ghahrem. differs from A. biarjmandicus Podlech & Zarre and A. inchebroonensis Maassoumi in having longer racemes with more flowers, only white trichomes on the calyx, and one pair of leaflets in the lower leaves and two pairs in the upper leaves. Astragalus gonabadensis Nasseh, Joharchi & F. Ghahrem. differs from A. baharensis F. Ghahrem. and A. macrobotrys Bunge in characters of the calyx and legume trichomes. Descriptions, distribution maps, and comparative tables of morphological characteristics for these taxa are presented. In addition, the first record of A. excedens Popov & Kult. in the flora of Iran is reported.

Influence of Surface Structure, Pigmentation and Particulate Matter on Plant Reflectance and Fluorescence.

Optical properties of plant leaves are relevant to evaluate their physiological state and stress effect. The main objective of this work was to study how variegation, pigment composition or reflective features modifies leaves' photophysical behavior. For this purpose, green leaves (Ficus benjamina), purple leaves (Tradescantia pallida), green leaves covered by white trichomes (Cineraria maritima) and variegated leaves (Codiaeum aucubifolium) were analyzed. Firstly, foliar surface morphology was evaluated by scanning electron microscopy. UV-vis and near-IR reflectance and transmittance spectra were obtained to calculate absorption (k) and scattering (s) coefficients. The theoretical approaches of Pile of Plates and Kubelka-Munk's theory resulted still valid for nonstandard leaves with differing surface conditions. However, frequently used spectral indices were not reliable for predicting water content, when leaves differed from conventional ones. The proportionality between the absorption factor and chromophore/pigment concentration was also lost for hairy leaves. A simplified model to describe these facts was presented here. Fluorescence spectra were recorded and corrected, due to light re-absorption. Water-optical parameter connection and pigment-optical parameter connection were thoroughly discussed. Leaf surface morphology and pigmentation have not only influenced the optical features of leaves but also played a role in the effect that particulate matter could cause on leaf photosynthesis.

<p><strong><em>Passiflora nana</em></strong><strong>, a new species in <em>Passiflora</em> section <em>Decaloba</em> (Passifloraceae) from northern Peru</strong></p>

A new species of Passiflora L. endemic to cloud forest in northern Peru, P. nana, is described and illustrated from living and herbarium material. The new species is similar to the Colombian P. erythrophylla in flower and Ecuadorian P. hirtiflora in vestiture. The indument is pilose to hispidulous throughout with long straight white trichomes, and the plant is short, less than 2.5 m long, with a very small flower ca. 1.5 cm diam. It is placed in subgenus Decaloba supersection Decaloba section Decaloba.

<p><strong><em>Hydrocotyle simulans</em></strong><strong> (Araliaceae), a new perennial species from south-eastern Australia</strong></p>

Hydrocotyle simulans, a new perennial species from south-eastern Australia, is here described with associated illustration, photographic images and distribution map. The new species is restricted mostly to freshwater swamps in coastal areas of south-eastern South Australia, southern Victoria and to the Furneaux Group of islands, off the north-eastern coast of Tasmania. Hydrocotyle simulans resembles both H. plebeya and H. pterocarpa, in having orbicular-cordate to reniform leaves, hydathodes along leaf lamina margins and broadly ovate to orbicular stipules with entire margins. It differs from these taxa by a combination of characters, such as reflexed white trichomes congregated at the petiole apices, ovate floral bracts with basal lobes, subsessile flowers with pale to dark crimson petals and lenticular mericarps with minutely rugulose surfaces when mature.

Crassula anso-lerouxiae, a new Species from the Robertson Karoo, Western Cape, South Africa

Crassula anso-lerouxiae, a new Crassula species, is described from the Succulent Karoo region between Worcester and Robertson. The linear obovate leaves in oblique pairs are not unlike C. cotyledonis, however, here the resemblance ends. C. anso-lerouxiae is distinguished by its much branched decumbent clustered growth of leaves covered in stiff recurved white trichomes, the margin obtuse and indistinct.

White plant shoots, wax-producing insects and other white structures made by arthropods: A mimicry complex?

Many insects masquerade as parts of plants, such as bark or leaves, or mimic poisonous organisms in order to defend themselves against predators. However, recent studies indicate that plants may mimic insects and other arthropods to deter herbivores. Here, I report visually similar white structures of plants and arthropods in Japan and suggest they are part of a mimicry complex. Young shoots covered with white trichomes or waxy substances may mimic wax-producing insects, such as woolly aphids, coccids and caterpillars, potentially resulting in reduced herbivory. Since wax-producing insects would reduce plant quality and quantity, be distasteful and attract natural enemies, herbivorous insects and mammals may avoid such white shoots. Furthermore, fungus-infected insects, gregarious braconid cocoons, spider egg sacs and froth made by froghopper nymphs or blasticotomid sawfly larvae are also conspicuously white and impose risks for herbivorous insects. Thus, these white structures may be mimicry models for white shoots and are likely to be part of a defensive mimicry complex. Although this study focuses on defence against herbivores, there are simultaneous physiological roles for white colouration that will not be discussed in depth here.

Português

The galls are characterized by an abnormal growth of tissues in response to galling specific stimuli. In this paper we described six gall morphotypes in Caryocar brasiliense (Caryocaraceae) present in individuals located on the campuses of Araguaina and Palmas, Federal University of Tocantins. All materials were analyzed using stereoscopic microscope and specific bibliography. In Araguaina, it was observed on the adaxial side of the leaflets, green-colored spherical morphotypes with purple apex and green-colored polypoid with brown patches and red apex. Green-colored globoid type galls with brown patches were observed on both surfaces. On the petiole, beige globoid galls were described. The aforementioned morphotypes are closed, hairless, had grouped occurrence and a single larval chamber with only one larvae per locule, except for the globoid leaf gall that presented cream trichomes and the globoid morphotype, located in the branches and in the petiole, which had two chambers. Aside from the polypoid gall, all the others showed full adherence. On the campus of Palmas it was recorded the fusiform morphotypes occurring in the primary and secondary veins, from the abaxial surface, varying its color from cream to red; and the pink-colored discoid located on the tertiary veins, on both surfaces; both showed full adherence, grouped occurrence and white trichomes; internally they display a larval chamber and only one larvae per locule. The morphological diversity of galls on C. brasiliense individuals demonstrates the potential of the species as a super-host in the Cerrado biome.

Dense white trichome production by plants as possible mimicry of arthropod silk or fungal hyphae that deter herbivory

Some spiders are well-known to mimic flowers or other plant surfaces in order to be cryptic to both their prey and their predators. We propose that dense, thread-like white trichomes of some plants from Estonia, Greece, Israel and Japan visually mimic spider webs, lepidopteran and spider-mite web nests and plant-pathogenic fungi, and that it may result in reduced herbivory, since various herbivores avoid spider- or other arthropod webs to circumvent predation or toxic attacks, or refrain from colonizing plants that have already been occupied by other herbivores and pathogens. Spiders and other web-forming arthropods are also the prey of certain vertebrate predators and wasps, and therefore such predators may be attracted to these web-like plant structures and prey on the invertebrate herbivores occupying them. We do not dismiss the possibility that these web-like structures may also have other defensive or physiological functions or that they are not classic mimics but rather exploit the herbivore׳s perceptual state concerning the avoidance of potentially risky objects.

Tylecodon opelii, a new obligatory quartz-gravel species from the Northern Knersvlakte (Western Cape, South Africa)

Some 47 species of Tylecodon are endemic to South Africa and Namibia (Van Jaarsveld & Koutnik 2004). In South Africa 43 species occur, confined to the south – and south-western portion of the country where winter rainfall is experienced. The new species falls within the Knersvlakte Centre of Plant Endemism (Van Wyk & Smith 2001). Tylecodon opelii is a new, obligate quartz-gravel dwelling species endemic to the northern Knersvlakte in the northern part of the Western Cape Province of South Africa. It was discovered by, and is named for, Conophytum expert Matt Opel, of the University of Connecticut (USA), on a expedition to the Knersvlakte July 2000. It is related to a group of dwarf, quartz-dwelling, geophytic species growing mainly in Succulent Karoo vegetation: Tylecodon nolteei, T. occultans, T. pusillus and T. peculiaris. Tylecodon opelii is immediately distinguished from other species by its oblong tubers, and its irregularly moulded leaves, which are intensely dark green during the growing season, bearing a few pointed trichomes. The corolla of T. opelii is cylindric to slightly funnel-shaped, 12-14 mm long, with tapering squamae at the base. The species can be confused with T. occultans and T. nolteei. However, T. occultans is immediately recognised by the white whiskery trichomes on its much broader leaf surfaces, T. nolteei (Fig. 1) by its blood-red, Gorbachev-forehead markings. T. occultans and T. opelii never have these painted markings, and T. nolteei has a larger, much taller caudex, though that pertains more to plants at the type locality; the eastern and southern populations show rounder, more modest caudexes. Tylecodon peculiaris (Fig. 2) is another very little-known plant with which T. opelii can also be confused, but it is immediately distinguished by its rough ‘jellytot’ appearance, the epidermis having a glassily bubbled purplish-green texture. Tylecodon opelii Van Jaarsv. & S.A.Hammer, differt a T. occultante tuberibus oblongis, foliis atroviridibus, irregulariter contortis, trichomata acuta sparse ferentibus, corolla 12–14 × 2–3 mm ad orem tubo alba differt. TYPE.—SOUTH AFRICA 3118 (Vanrhynsdorp): Bakoondkolk, south-sloping quartz gravel hillside, 150–200 m, (–AB), Van Jaarsveld 22751 (NBG, holo.). Plant solitary, summer-deciduous, dwarf geophyte to 10 mm in diameter. Roots fibrous. Tuber oblong, up to 35 × 10–15 mm, pale grey-brown and somewhat flaking, exposing the grey-green epidermis underneath; phyllopodia absent. Leaves softly succulent, apically produced, solitary or rarely with up to 3 leaves, ascending; blade irregularly molded, broadly club-shaped, orbicular to reniform (viewed from the top), often irregularly concave or shallowly grooved, 8–15 × 10–15 mm, cuneate and

Two New Species of Doliocarpus (Dilleniaceae) from Colombia

ABSTRACT Doliocarpus schultesianus Aymard from moist forests in the upper Rio Negro region (Vaupes department) and D. triananus Aymard from montane forests in Antioquia department, Colombia, are described, illustrated, and compared to their closely related species. Doliocarpus schultesianus is not evidently allied to any other Doliocarpus Rolander species; this new species has inflorescences produced from short shoots (brachyblasts) and young fruit completely covered by stinging yellow trichomes. Doliocarpus triananus is most similar to D. pipolyi Aymard due its chartaceous leaves with margins dentate along the blade and its papyraceous basal bracteoles, but it differs from that species in its leaf and sepal shape, dense pubescence along the midrib and secondary nerves on the lower surface, peduncle patent-pilose, and fruit 10–12 mm in diameter, completely covered by white trichomes. An updated key to the 19 species of Doliocarpus from Colombia is provided.

Note on Astragalus sect. Incani (Fabaceae) in Iran

Astragalus hashtrudicus Ranjbar, a single new species endemic to Iran, is described and illustrated. The new species belongs to subgenus Cercidothrix Bunge, section Incani DC., in Astragalus L. and seems to be distinct among the Iranian species. Astragalus hashtrudicus is distributed in northwestern Iran in the Azarbaijan Sharqi province. It is closely related to A. prilipkoanus Grossheim and is distinguished by its pods that are rather densely covered with appressed white trichomes and its leaflets that lack minute dark reddish dots. The conservation status is evaluated as VU (Vulnerable) according to IUCN criteria.

Una nueva especie de Pellaea (Pteridaceae) del estado de San Luis Potosí, México

Se describe e ilustra Pellaea ribae Mendoza & Windham, una nueva especie de Pellaea sect. Pellaea la cual se distingue claramente de otros representantes del género por sus abundantes tricomas blanquecinos presentes en el pecíolo, en el raquis y en la superficie abaxial de la lámina. Hasta ahora P. ribae se conoce solamente de dos localidades en San Luis Potosí, México. Se discuten las posibles relaciones de esta nueva especie con otros helechos cheilantoides.

Rudgea tayloriae (Rubiaceae), an Unusual New Species from the Eastern Slopes of the Venezuelan Andes

Rudgea tayloriae (Rubiaceae), a new species from the eastern slopes of the Venezuelan Andes, is described and illustrated, and its relationships are discussed. Rudgea Salisbury is a neotropical genus of ca. 150-170 species (Dwyer, 1980; Taylor et al., 1991; Taylor, 1996), most of which are South American. Andersson's (1992) checklist of neotropical Rubiaceae included 214 species names, but his objective in compiling the list was not to make taxonomic decisions, and a number of the names he cited are clearly synonyms. Steyermark (1974) recognized 28 species of Rudgea in his treatment of the Venezuelan Rubiaceae. Subsequently, Steyermark (1981, 1988) described an additional four species of Rudgea from Venezuela. The valvate corolla lobes, 2-celled ovary, and fleshy drupe with two pyrenes place Rudgea in the subfamily Rubioideae tribe Psychotrieae A. Richard ex Dumortier (Robbrecht, 1988; Taylor, 1996). Rudgea is similar to Palicourea Aublet and Psychotria L., but it usually can be separated from these closely related genera by the pectinate or fimbriate appendages on its stipules (Steyermark, 1974; Standley & Williams, 1975; Dwyer, 1980; Taylor, 1996). This stipule character, however, can present practical problems in identifying material since the stipules frequently are caducous, as has been noted earlier by Taylor et al. (1991). Rudgea tayloriae Aymard, Dorr & Cuello, sp. nov. TYPE: Venezuela. Trujillo: Dtto. Bocon6, Parque Nacional Guaramacal, selvas nubladas de la vertiente sur, aprox. 9012'45N, 70009'51W, 2300 m, 3-5 Jan. 1996 (fl, fr), N. Cuello, R. Gonzdlez, C. Orda & A. Gonzdlez 1350 (holotype, PORT; isotypes, MO, US, VEN). Figure 1. Species nova quae a Rudgea hospe Standley & Steyermark floribus sessilibus, corollis purpureis, tubo 3-4 mm longo, lobis 1-1.5 mm longis, filamentis ca. 1 mm longis, papillatis, basi tubi affixis, antheris ca. 2.5-3 mm longis, stigmate furcato differt. Small trees to 8 m tall, branches and branchlets glabrous throughout. Leaves opposite, decussate; blades elliptic to ovate-elliptic, 5-11 cm long, 2.57 cm wide, acuminate at apex with the tip up to 22.3 mm long, acute at base, margin entire, glabrous and well reticulated on upper surface, glabrous underneath, except along the midrib and lateral nerves, which are sparsely appressed-pubescent to puberulent when mature, lateral nerves 7-10 pairs, convergent and linking toward margin; petioles 513 mm long, ca. 1 mm thick, subcanaliculate, sparsely appressed-pubescent at first, glabrous when mature. Stipules interpetiolar, ciliate, caducous, briefly persistent only on uppermost 1-2 nodes, united around the stem into a cupuliform st ucture, 1.5-4 mm long, rounded to truncate apically, sparsely appressed-pubescent at first, glabrous when mature, with 6-8 projections ca. 1 mm long. Inflorescences terminal, spiciform to subcapitate, 1.5-2.5 cm long (or unexpanded?), appressed-pubescent with white trichomes; bracts subtending the flowers subulate, 4-8 mm long, apex with the tip 0.5-2 mm long, shortly appressed-pubescent externally, glabrous internally. Flowers sessile, calyx ca. 2 mm long, cupuliform, puberulent to densely appressed-pubescent at the base exterNovoN 9: 315-317. 1999. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 05:39:12 UTC All use subject to http://about.jstor.org/terms

Brachystelma bracteolatum (Asclepiadaceae), a New Species in Nigeria

Summary. A new species of Brachystelma Sims from the Jos Plateau in Nigeria, B. bracteolatum Meve, is described and illustrated. The new species resembles the W African B. constrictum and the E African B. lineare in its grass-like leaves, but is quite different in its corona structure. According to Meve & Porembski (1993), Brachystelma Sims (Asclepiadaceae-Stapelieae) is represented in West Tropical Africa by eight out of about a hundred species known for the genus. Except for B. mortonii C. C. Walker, which is restricted to Ghana and the Ivory Coast, all have been found in Nigeria, although none is endemic there. Recently, material of an undescribed taxon has been collected in Nigeria and is described here. Brachystelma bracteolatum Meve sp. nov. B. constricto J. B. Hall habitu affinis, sed corolla coronaque glabris, lobis coronae staminalibus rectis 2 mm longis, lobis coronae interstaminalibus deltoidibus, parvis differt. Typus: Nigeria, Jos Plateau, Specks 549 (holotypus K; isotypus MSUN). Dwarf, perennial geophyte. Rootstock a hypocotyl tuber, 15 - 25 x 50 - 120 mm, discoid, surface smooth, grey-brown. Stems repeatedly di- or trichotomously branched from the base, prostrate to erect to 10 - 20 cm, rather soft and flexible, 1 - 1.5 mm diam., bright green or reddish, sparsely covered with recurved, translucent white trichomes c. 50 pm long. Leaves linear, acute, subsessile, 30 - 60 x 1 mm, spreading, soft, slightly fleshy, adaxially slightly grooved along the midrib, green, glabrous except for a few recurved trichomes on the abaxial side of the rachis; stipular glands present, attached to the stems. Inflorescences bostrychoid, geminiflorous, extra-axillary, sessile, initially terminal, though quickly pushed aside by the proliferating main stem, 4 partial inflorescences arranged around the swollen, c. 3 mm wide nodes, forming 8-flowered synflorescences, flowering ? synchronously. Floral bracts c. 2.5 mm long, translucent white with reddish tinge, one per partial inflorescence, persistent, occasionally with one stipular gland developed, bracteoles 1 - 1.5 mm long, 1 or 2 per flower, persistent, estipulate. Pedicels 4 - 6 x 1 mm, covered with recurved trichomes 50 pm long. Calyx free,

A New Species of Stenandrium (Acanthaceae) from Grão-Mogol, Minas Gerais, Brazil

A new species, Stenandrium stenophyllum, is described and illustrated. It is related to S. hatschbachii Wasshausen but differs markedly from that taxon by its 3-verticillated leaves with narrow, linear-lanceolate blades. Both species are known only from Grao-Mogol, Minas Gerais, Brazil. Stenandrium is a genus of perennial herbs and subshrubs with about 70 species that occur in tropical America and Africa, including Madagascar (Vollesen, 1992). In Brazil there are about 16 species, most of which grow in grasslands and savanna-like vegetation. During work on the floristic inventory of the Campos Rupestres vegetation in Grao-Mogol, Minas Gerais, coordinated by the Universidade de Sno Paulo, a new species of Stenandrium that shows close affinities to S. hatschbachii Wasshausen was found. Stenandrium stenophyllumn Kameyama, sp. nov. TYPE: Brazil. Minas Gerais: Grao-Mogol, Estrada para CristAlia a ca. 800 m da ponte sobre o rio Itacambirugu, ca. 750 m alt., 16o36'S 42055'W, 14 jun. 1990 (fl, fr), A. A. Oliveira, D. C. Zappi, J. R. Pirani & R. Simdo-Bianchini CFCR 12982 (holotype, SPF; isotypes, K, MBM, RB, US). Figures 1, 2. A S. hatschbachii Wasshausen cuj affinis sed foliis 3-verticillatis, linear-lanceolatis vel linearibus vel linearfalciformibus differt. Caulescent subshrub 0.4-1.5 m tall, erect to decumbent. Stems terete, densely pubescent with white trichomes, 0.20-0.25 mm long. Leaves whorled, 3 at each node, sessile to subsessile, coriaceous, the blades linear-lanceolate to linear, sometimes linear-falcate, 3.5-6.0 cm long, 2-5 mm broad, attenuate at base, obtuse to acute at apex, sometimes acuminate or shortly mucronate, the upper surface dark green, sparsely and inconspicuously puberulous with very short eglandular trichomes, the lower surface paler green, inconspicuously puberulous with eglandular and glandular trichomes, the margin revolute. Inflorescence of terminal and subterminal spikes to 2.5 cm long, the spikes sessile or borne on peduncles to 6 mm long, pubescent like the stems, except with trichomes shorter (i.e., 0.15 mm long); the flowers opposite along the spike axis; bracts subulate, 4-6 mm long, 0.5 mm broad, pubescent like the leaves; bracteoles subulate, 4 mm long, 0.5 mm broad, pubescent like the leaves, calyx deeply lobed, 5-7 mm long, the lobes lanceolate, 1.2 mm wide, very sparsely pubescent; corolla whitish lilac to purple-red, 9-12 mm long, the tube 5-6 mm long, the upper lip pale pink to white, the lobes 3 mm long, the lower lip dark purple, the central lobe 5-5.5 mm long, the lateral lobes 4.2-4.8 mm long, stamens 1.3-1.7 mm long; a thers 1.1 mm long; pollen grains tricolpate, prolate, 49.4 x 33.5 /.m, exine tectate-perforate, colpi membranes sparsely granulate; style filiform, stigma subclavate, asymmetrical. Capsule ellipsoid, 1.2 cm long, inconspicuously puberulous; seeds laterally flattened, semi-elliptic in outline, 3 mm long, 2 mm wide, densely pubescent with long, appressed trichomes bearing minute lateral barbs. Stenandrium stenophyllum is closed allied to S. hatschbachii (Wasshausen, 1990): both species have similar inflorescences and flowers, but S. hatschbachii can be easily distinguished by the opposite, broader (9-14 mm broad), lanceolate to oblong leaves. In contrast, the leaves of the new species are 3-verticillate, linear-lanceolate to linear, 2-5 mm broad. Both species grow among shrubs and small trees in dense and drier vegetation on sandy soils with rocky outcrops. Both species have been collected only in Grao-Mogol. Paratype. BRAZIL. Minas Gerais: Grio-Mogol, vale do Rio Itacambirugu, ao longo da estrada para Cristilia, 10 Nov. 1989, J. R. Pirani, P T Sano, T R. S. Silva & A. Freire-Fierro CFCR 12420 (SPF). Acknowledgments. I am grateful to M. A. CruzBarros and the staff of the Segao de Dicotiled~neas, Instituto de Botanica de Sao Paulo for help with the NovoN 6: 268-270. 1996. This content downloaded from 157.55.39.191 on Tue, 11 Oct 2016 04:54:11 UTC All use subject to http://about.jstor.org/terms Volume 6, Number 3 Kameyama 269 1996 Stenandrium stenophyllum from Brazil

Floral mimesis inThelymitra nuda (Orchidaceae)

Insect pollination occurred inThelymitra nuda R. Br. on sunny days when the ambient temperature exceeded 20 °C. The flower buds on a raceme opened subsynchronously displaying the brightly-colored, actinomorphic perianth and exposed the contrastingly-colored, scented and ornamented column. InT. nuda the staminodes and the filament of the fertile stamen are fused to one another producing an inflated hood over the anther. This staminodal hood is terminated in two non-ornamental, but brightly-colored, central lobes and two terete lateral lobes bearing approximately 400 white trichomes. Each trichome bears a double chain of 30–40 spherical, rugulose cells. Female bees, in the genusLasioglossum (Halictidae), were observed to land directly on the hood and curled their bodies around the four lobed tip of the staminodal complex. The bees attempted to forage on the lobes as if they were collecting pollen from fertile, poricidal stamens. These bees applied thoracic vibration to the yellowish central lobes and actively scraped the trichome clusters (Pseudopollen) with their forelegs. Bees carried the pollinaria ofT. nuda dorsally on their abdomens. Abdominal contact with the rostellum appeared to occur when the female bee disengaged herself from the staminodal hood. Observations made of bees on co-blooming flowers, and analyses of pollen loads collected by bees suggested that the orchid flower mimics the guild of blue-purple flowers that lack floral nectar but offer pollen in poricidal anthers. The models ofT. nuda are co-bloomingLiliaceae in the generaDichopogon andThysanotus. However, nectarless, buzz-pollinated flowers are also extensively distributed over the orchid’s range. More than 30% of the flowers in theT. nuda population had their pollinaria removed, suggesting a high capacity for cross-pollination in an orchid genus usually considered to be self-pollinated via mechanical autogamy. This study confirmed previous predictions that column modifications represented a trend towards pseudanthery.