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Summary Spatial distribution, pollen-flow and the factors affecting seed-set were studied for a population of the distylous perennial Linum perenne L. during a single season. The morphs were spatially segregated at the site. Stigmatic pollen loads on long-style plants comprised 27 to 51 % legitimate pollen and on short-style plants 0 to 46% legitimate pollen. Most flowers received more legitimate pollen grains than the number theoretically required to fertilize the corresponding number of ovules. Intraflower pollinations accounted for a large proportion of individual stigma loads. There was a weak negative correlation between the distance of the nearest legitimate neighbour and the number of legitimate pollen grains recorded on the stigma. No relationship was established between either the proximity or proportion of legitimate neighbours and seed-set. Long-style plants produced less pollen and matured more seeds than short-style plants. It is suggested that, in the population studied, paternal (pollen) and maternal (seed) investment are unequally divided between the morphs. This may be a common theme associated with heterostyly in plants.

International audience; 8 Aims: Soil temperature and moisture impact plants not only during growth and survival but also 9 during seed germination and interaction of seeds with the chemical environment. The quantitative 10 impacts of either temperature and moisture or plant specialized metabolites (PSM) on germination 11 are widely studied. However, the combined effect of PSM and moisture or temperature on 12 germination remains poorly understood. 13 Methods: We addressed this issue by studying the effect of PSM extracted from four Mediterranean 14 woody plants on germination speed and final percentages of a subordinate herbaceous plant, Linum 15 perenne. 16 Results: By using hydro-and thermal time threshold models, we show how PSM interact with 17 temperature and moisture levels to limit germination at dry and upper thermal limits, with the 18 magnitude of effects depending on the source plant. PSM effects on germination, also observed on 19 natural soils, persisted after their removal from the seed environment. 20 Conclusions: We conclude that the impact of climate change on reproduction of herbaceous plants 21 can be modulated by effects of PSM from woody plants, which might exacerbate the negative 22 impacts of global changes on biodiversity. 23

Introduction Hairy root cultures of Linum sp. are an alternative for the high production of lignans. Linum perenne is known to produce arylnaphthalene-type lignans such as justicidin B, isojusticidin and diphyllin. Objective To elucidate the presence of aryltetralin-type lignan diastereoisomers, besides the known arylnaphthalene-type lignans, in hairy roots of Linum perenne, and to determine the configurations of one diastereoisomer of 6-methoxypodophyllotoxin (6-MPTOX). Methods Lignans from hairy root cultures of Linum perenne were extracted and separated by HPLC. Arylnaphthalene-type lignans were identified by LC-MS, according to the literature. Two diastereoisomers of aryltetralin-type lignans were analysed by mass spectrometry and NMR spectroscopy. Results Numerous arylnaphthalene-type lignans (diphyllin-2-hexose-pentose, diphyllin-3-pentose and diphyllin-hexose) were identified in hairy root cultures. Methoxypodophyllotoxin, an aryltetralin-type lignan, was also identified, as well as one diastereoisomer. This aryltetralin-type lignan could be derived via 7-hydroxymatairesinol as a hypothetical biosynthetic pathway. The stereochemical configurations of aryltetralin isomers were determined. Conclusion Arylnaphthalene and two diastereoisomers of aryltetralin-type lignans are produced in Linum perenne hairy root cultures. Matairesinol, the precursor of justicidin B, also seems to be converted into 6-MPTOX via 7-hydroxymatairesinol. This is the first report of the stereochemical configurations of an aryltetralin-type lignan other than podophyllotoxin (PTOX). Copyright © 2015 John Wiley & Sons, Ltd.

Проведена оценка фитотоксичности меди для декоративных видов льна – Linum grandiflorum Desf. (сорта Атласный Голубой, Голубой, Рубрум), Linum perenne L. (сорта Синий шелк, Диамант, Небесная лазурь). Угнетение декоративных видов льна наблюдалось в водных опытах уже при концентрациях меди 20-30 мг/л, корневая система не образовывалась у большинства сортов при содержании 50 мг/л. В почве у большинства исследуемых сортов существенное ингибирование наблюдалось при концентрации – 50 мг/кг. По результатам работы выделены сорта обладающих высокой (Рубрум, Диамант, Небесная лазурь) и средней чувствительностью (Голубой, Синий шелк) к концентрациям меди более 50 мг/кг. Данные сорта возможно использовать в местах невысокой техногенной нагрузки (парках, скверах, на придомовых территориях)., An estimation of the phytotoxicity of copper ions for Linum grandiflorum Desf. (cultivar Satin Blue, Blue, Rubrum), Linum perenne L. (cultivar Blue silk, Diamond, Celestial Azure). Compared with the control samples, the inhibition of flax was observed in aqueous experiments already at a concentration of 20 -30 mg/l. The root system was not formed in most varieties at a concentration of 50 mg/l. In soil, in most of the plants under study, significant inhibition was observed at a concentration of 50 mg/kg. Thus, we have identified varieties with high (Rubrum, Diamant, Celestial Azure) and medium sensitivity (Blue, Blue silk) to copper concentrations of more than 50 mg/kg. These varieties can be used in places of low man-caused load (parks, squares, on the adjacent territories).

Question What is the relative significance of seed source, growth form and seeding density in contributing to restoration of calcareous grasslands? Location Experimental field site on calcareous gravel in the lowlands north of Munich (S Germany). Methods The research question was investigated using a dominant grass (Festuca rubra) and three subordinate forbs (Buphthalmum salicifolium, Dianthus carthusianorum, Linum perenne). A randomized split-block design consisting of six blocks was established with two growth forms of F. rubra (rhizomatous, tussock) from two sources (cultivars, ‘regional’ plants from the region of the field experiment) seeded at two densities (800, 1600 seed·m−2) and inter-seeded with forbs from cultivar and regional sources (100 seed·m−2). Each combination of plant source, growth form and seeding density of the dominant species was replicated six times. Individual numbers of F. rubra (Year 1), the subordinate species (Year 1 and Year 2) and the spontaneously invading alien plant Erigeron annuus (Year 2) were counted, and total cover of vascular plants in each subplot and average number of flowers per area were recorded in Year 2. Results Regional seed generally had higher establishment than the cultivar counterpart in both the dominant and subordinate species. Growth form and seeding density of F. rubra differed little in their effects on establishment of the forbs, but fewer E. annuus invaded subplots with regional F. rubra, and subplots with the tussock growth form. Only in D. carthusianorum did regional rather than cultivar subordinates produce more flowers. Conclusions Seed source and growth form are the most significant factors for designing seed mixtures for restoration of calcareous grasslands.

According to the cultivar vigour hypothesis, cultivars are frequently selected for traits such as increased biomass and resource capture, which may hinder the establishment of non-cultivars. Despite this concern, cultivar seed material is still used in grassland restoration. An alternative is wild plant material, which is commercially produced and used in the respective region (‘regional seed’). We established a greenhouse experiment to examine the performance of cultivar and regional forb species with and without competition from cultivar and regional dominant grass species. This was conducted in order to understand the potential effects of sowing cultivar seed in grassland restoration projects. Three calcareous grassland forb species (Buphthalmum salicifolium, Dianthus carthusianorum and Linum perenne) and one dominant grass species (Festuca rubra ssp. commutata) were selected. One forb species was sown in the centre of each pot and either zero, two or four F. rubra ssp. commutata individuals were planted around it. Above-ground biomass, plant height, leaf length, leaf width, number of leaves and stems were measured. When grown without competitors, each forb species performed differently with only L. perenne exhibiting cultivar vigour. Cultivar forbs were less negatively affected by competition with F. rubra ssp. commutata than their regional counterparts, thus supporting the cultivar vigour hypothesis. Overall, regional F. rubra ssp. commutata suppressed the above-ground biomass of the forbs species more than the cultivar F. rubra ssp. commutata, thus highlighting the potential competitiveness of regional seed. Ultimately, the goals of the restoration project will determine the source of seed material to be used in the project. Due to the complex nature of the issues involved in restoration, it should be considered that the reliance on simple guidelines in relation to the source of seed material used in grassland restoration has its limitations.

Mature seeds of 20 Linum species were analyzed for their content of lignans. The seeds of common flax (Linum usitatissimum L.) are known to contain as characteristic lignan sesoisolariciresinol diglucoside (SDG), whose presence in seeds of some other Linum species has also been reported. In order to investigate the material for the presence of such very polar lignans as well as for less polar non-glycosidic lignans as frequently found in aerial parts of Linum species, polar and non-polar extracts of each sample were analyzed by HPLC/ESI-MSMS. SDG was detected in 15 of 16 investigated seed samples of taxa representing sections Linum and Dasylinum. None of eight samples of taxa from sections Syllinum and Linopsis contained detectable amounts of SDG. Quite interestingly, most of the SDG-positive samples contained the 8R,8'R-isomer exclusively while only three (including L. usitatissimum) contained the 8S,8'S-stereoisomer as the predominant form. As a most noteworthy finding, the dichloromethane extracts obtained from seeds of several Linum species were found to contain significant concentrations of non-polar cyclolignans of the arylnaphthalene/-dihydronaphthalene lactone type or, alternatively of the aryltetralin lactone type. Thus, seeds of Linum perenne L. as well as those of several other representatives of sections Linum and Dasylinum were found to contain significant concentrations of the arylnaphthalene justicidin B along with further compounds of this type and some aryldihydronaphthalene-type lignans. On the other hand, seeds of Linum flavum and further representatives of section Syllinum were found to contain aryltetralin-type lignans, mainly in the form of esters with aliphatic carboxylic acids, such as 6-methoxypodophyllotoxin-7-O-n-hexanoate, whose occurrence in L. flavum seeds has very recently been reported by us for the first time. Various chemosystematic and biogenetic aspects are discussed in the light of these results.

A new heterostylous species, Linum katiae, is described from Calabria (southern Italy). This species differs from the closely related Linum alpinum − occurring in Alps and Apennines − by leaf width (3.1 ± 0.5 mm vs. 1.6 ± 0.4 mm), different flower color (bluish-white vs. blue), petals' size (25.8 ± 1.3 mm vs. 16.0 ± 4 mm), sepals' size (9.4 ± 0.7 mm vs. 6.1 ± 1.2 mm), and stigma shape (2.5 vs. 1.4–1.5 length/width ratio). The taxonomic relationships of the new species with Linum perenne group representatives (L. alpinum, Linum austriacum, Linum punctatum) and with other sect. Linum taxa (i.e. Linum narbonense) are discussed.

This article summarizes information on the taxonomy of 'Appar', a perennial blue flax cultivar ( Linum perenne L. [Linaceae]), and characteristics that distinguish it from native Lewis flax ( Linum lewisii Pursh [Linaceae]). 'Appar' apparently originated as a European flax that escaped from garden cultivation. Randomly amplified polymorphic DNA (RAPD) analysis places 'Appar' with other collections of European Linum perenne and separates it from native North American collections of Lewis flax. Morphologically, 'Appar' differs from Lewis flax in having an intense blue petal color, shorter internodes, leaves that point upward along the stem, and multiple slender stems suffused with red near the base. The heterostylous reproductive system, which it shares with its European cousins, keeps 'Appar' reproductively isolated from native populations of Lewis flax. All available data indicate that 'Appar' is not invasive and does not pose a threat to native flax populations. Ease of establishment, seed production, and showiness of the abundant flowers recommend 'Appar' for use in xeriscape plantings. Alternatively, the recent germplasm release of Lewis flax, 'Maple Grove', also establishes readily from seed and can be effectively used when objectives dictate the exclusive use of native germplasms.

The ‘Appar’ flax germplasm was originally released by the USDA Soil Conservation Service as a cultivar of Linum lewisii. The observation that ‘Appar’ is heterostylic, a key taxonomic character distinguishing Lewis flax from other members of the Linum perenne complex, created a need for further study in order to resolve the taxonomic position of both Lewis flax and the ‘Appar’ cultivar. We grew 10 plants each of nine European, nine North American, and three putative ‘Appar’ seed sources, measured 18 morphologic variables on each plant, and examined genetic variation using randomly amplified polymorphic DNA (RAPD). We also performed self‐ and cross‐pollinations within and among source groups. North American collections differed from European collections for 12 of the 18 morphologic variables. ‘Appar’ collections were morphologically similar to European collections and differed from North American collections for 13 of the 18 variables. RAPD data also showed that ‘Appar’ sources clustered with European, and ...

From the dichloromethane extract of aerial parts of Linum perenne L. (Linaceae), in addition to three lignans of the arylnaphthalene type (justicidin B, isojusticidin B and retrohelioxanthin), we isolated four lignans of the aryldihydronaphthalene type. The major constituent contains a novel type of ring closure, formed by additional cyclisation between rings A and D of the aryldihydronaphthalene skeleton via an oxymethylene bridge, yielding a novel 2,8-dihydro-3 H-benzo[ E]naphtho[1,8- BC]oxepine ring system hitherto unreported for a lignan or any other natural product. We named this novel unusual lignan linoxepin. In addition, three further aryldihydronaphthalenes (one new and two known) were isolated. The absolute stereochemistry at C-8 of linoxepin and the related dihydronaphthalene lignans was established as R on grounds of CD spectra which were in good agreement with results of time dependent density functional (TDDFT) quantum mechanical simulations. The occurrence of aryldihydronaphthalenes in the genus Linum or the Linaceae has not been reported before.

Zinc toxicity thresholds for reclamation plants are largely unknown. As a result, ecological risk assessments often rely on toxicity thresholds for agronomic species, which may differ from those of restoration species. Our objective was to provide Zn toxicity thresholds for forb species that are commonly used in reclamation activities. We used a greenhouse screening study where seedlings of yarrow (Achillea millefolium L.), Bigelow's tansyaster (Machaeranthera bigelovii (Gray) Greene var. bigelovii), blue flax (Linum perenne L. var. Appar), alfalfa (Medicago sativa L. var. Ladak), Palmer's penstemon (Penstemon palmeri Gray), and Rocky Mountain penstemon (Penstemon strictus Benth. var. Bandera) were grown in sand culture and exposed to increasing concentrations of Zn. Lethal concentrations (LC50 – substrate Zn concentration resulting in 50% mortality), effective concentrations (EC50 – substrate Zn concentration resulting in 50% biomass reduction), and phytotoxicity thresholds (PT50 – tissue Zn concentration resulting in 50% biomass reduction) were then determined. Phytotoxicity thresholds and effective concentrations for these reclamation species were relatively consistent between species. Our estimates of PT50-shoot for these species range from 1258 to 3214 mg Zn kg−1 . Measures of EC50-plant for these restoration forbs ranged from 82 to 214 mg Zn L−1 . These thresholds might be more useful for risk assessors working on reclamation sites than those based on non-reclamation species that are widely used.

Perennial grain crops were examined in pure stands and in various mixtures for their grain yield potential in, and suitability for, low-input systems on marginal land. The investigation was based on field experiments conducted at two sites characterized by marginal environmental conditions in south-west Germany in 1999 and 2000. The experiments included perennial species of rye (Secale cereale x Secale montanum), intermediate wheatgrass (Thinopyrum intermedium), lupin (Lupinus polyphyllus) and linseed (Linum perenne). In some stands, white clover (Trifolium repens) was included as an undersown intercrop for improved N supply. It was found that maturation of the species differed by up to almost 6 weeks, and consequently the threshability of most mixed stands was not satisfactory. Nevertheless, mixtures of either of the grasses (rye or wheatgrass) with lupin or undersown clover proved to be more suitable than pure stands in most cases, for measures such as grain yield, weed suppression and stability of grain yield over years. The grain yield harvested in the experiments in 1999 was low, reaching about 2.7 t ha -1 with rye, and decreased for most species in 2000. If improved genotypes were available, perennial grain crops could provide an alternative for arable cropping and set-aside areas under marginal conditions.

The plant breeders usually rescue inherently weak, immature or hybrid embryos to prevent degeneration. The successful production of plants from the cultured embryos largely depends upon the maturation stage and the composition of the medium. Abortion of embryos at one or the other stage of development is a characteristic feature of distant hybridization. For the first time successful embryo culture to obtain an interspecific cross between Linum perenne × L. austriacum was demonstrated by Laibach (1925, 1929). Since then several refinements have been made in embryo culture/embryo rescue techniques which have been a popular approach for raising hybrids from a number of incompatible crosses. Currently embryo rescue holds great promise not only for effecting wide crosses, but also for obtaining plants from inherently weak embryos, obtaining haploid plants as well as for shortening the breeding cycle.

Linum perenne L. is a nonclonal perennial herb widely distributed across a range of habitats. Variation in seed germination patterns was examined for 21 Intermountain collections and for the commercial cultivar 'Appar'. Collections from sites with long, snowy winters were largely dormant at harvest and responded positively to chilling. Collections from middle elevation sagebrush-grassland sites were generally nondormant and contained a fraction induced into secondary dormancy by chilling. Collections from palouse prairie and pinyon-juniper sites were generally nondormant and unaffected by chilling, as was 'Appar'. When seeds of contrasting populations were planted in seed retrieval experiments at low, middle, and high elevation sites, their field germination phenology was predictable from laboratory experiments. In common garden experiments, there were significant among-sibship differences in germination for each garden-grown wild accession but not for 'Appar', suggesting that differences both among and within populations may be genetically based. Garden-grown seeds were generally less dormant than wild-collected seeds, possibly because of selection during propagation. Results demonstrated the existence of ecologically relevant among-population and within-population variation in germination phenology for blue flax. Seeds of high-montane populations are spring-emerging and have little provision for between-year carryover. Populations from lower elevation habitats with less predictable weather have seeds with contrasting germination patterns, allowing for emergence in both fall and spring as well as for seed bank carryover. 'Appar' seeds lack these predictive and carryover mechanisms.

Linum perenne Linnaeus, Species Plantarum 1: 277. 1753. "Habitat in Sibiria et Cantabrigiae." RCN: 2205. Lectotype (Ockenden in Watsonia 8: 209. 1971): Herb. Linn. No. 396.8 (LINN). Current name: Linum perenne L. (Linaceae)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part L), pp. 610-650 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 634, DOI: 10.5281/zenodo.291971

Cell suspension cultures of Linum perenne L. Himmelszelt accumulate justicidin B as the main component together with glycosides of 7-hydroxyjusticidin B (diphyllin). A hypothetical biosynthetic pathway for these compounds is suggested. Justicidin B 7-hydroxylase (JusB7H) catalyzes the last step in the biosynthesis of diphyllin by introducing a hydroxyl group in position 7 of justicidin B. This enzyme was characterized from a microsomal fraction prepared from a Linum perenne Himmelszelt suspension culture for the first time. The hydroxylase activity was strongly inhibited by cytochrome c as well as other cytochrome P450 inhibitors like clotrimazole indicating the involvement of a cytochrome P450-dependent monooxygenase. JusB7H has a pH optimum of 7.4 and a temperature optimum of 26 degrees C. Justicidin B was the only substrate accepted by JusB7H with an apparent K(m) of 3.9+/-1.3 microM. NADPH is predominantly accepted as the electron donor, but NADH was a weak co-substrate. A synergistic effect of NADPH and NADH was not observed. The apparent K(m) for NADPH is 102+/-10 microM.

A cDNA encoding a pinoresinol-lariciresinol reduc- tase PLR (PLR-Lp1) was isolated from a cell culture of Linum perenne Himmelszelt accumulating the arylnaphthalene lignan justicidin B. The recombinant PLR-Lp1 prefers (+)-pinoresinol in the first reaction step, but (� )-lariciresinol in the second step. Therefore, it is the first PLR described with opposite enantio- specificity within the two reaction steps catalysed by PLRs. Hairy root lines transformed with an ihpRNAi construct to sup- press plr gene expression show less mRNA accumulation for the plr-Lp1 gene and PLR enzyme activity. Justicidin B accumula- tion was reduced down to 24% in comparison to control lines showing the involvement of PLR-Lp1 in the biosynthesis of jus- ticidin B. � 2007 Federation of European Biochemical Societies. Pub- lished by Elsevier B.V. All rights reserved.

Summary Sharp discontinuities in chromosome number and type of breeding system provide more satisfactory characters for classifying the members of the Linum perenne group than most of the morphological characters which have been used in the past. Pollen morphology has great taxonomic value here because it can be used to distinguish diploids from tetraploids and inbreeders from outbreeders. Of seventy European topodemes examined, fifty-seven are diploid (2n= 18) and fourteen are tetraploid (2n= 36). The pollen grains of the diploids have three furrows and those of the tetraploids have six pores. All of the European members of the group are heterostylous and self-sterile, except for L. leonii, which is homostylous and self-fertile and endemic to Erance and Western Germany. Artificial hybrids between most of the European members of the group have been produced and their pollen fertilities recorded. No absolute sterility barriers have been found and the whole group is equivalent to a single coenospecies. The course of evolution in the group is considered in the light of all the available evidence.

1. The material used in this investigation is the pollen mother cells of Linum perenne, L. which were fixed in BOUIN'S solution. Sections were cut at seven micra and stained with iron-alum-haematoxylin. 2. As shown in Figs. 3 and 4, the pairing spireme of the diplotene stage divides into four sections with a slender neck in the middle of the threads. Probably this is the origin of the tetrad chromosomes. Towards the end of the diplotene stage the spireme gradually contracts developing into the more compact gemini of the following diakinesis. Consequently in the, early shorty afterward, by the end of the dickinesis, the tedrad chromosomes becomc more contracted diakinesis, as shown in Figs. 5 and 6, the slender part of the spireme (gemini) becomes some-what obscured. But in the late diakinesis when the pairing gemini have contracted further and become more or less roand, there appears a narrow crack in the middle part of each of the pair dividing them into four sections (Fig. 7 a). These four are the tetrad chromosomes. But shortly afterward, by the end of the dickinesis, the tetrad chromosomes become more contracted and form the double chromosomes of the first metaphase (Figs. 7 a and 9). 3. Sometimes during the late diakinesis ring shaped chromosomes are formed by the joining of the pairing gemini at the ends (Fig. 8 a). Though the formation of these fings is sometimes very obscure, it is probable that they are the tetrad chromosomes. After continued contraction these rings gradually change into the double chromosomes of the first metaphase (Figs. 8b and 9). 4. In view of the arrangement of the pairing spireme in the diplotene stage (Figs. 2, 3, and 4), it appears that in Linum perenne we have an instance of parasynapis which is so rare in plant cytology that it invites further study.

ALONG WITH Linum perenne, considered in a previous article (Esau, 1943a), certain other plants were examined to determine the course of development of the first vascular elements in vegetative shoots. The present paper describes the differentiation of the first phloem and xylem in the shoots of Helianthus annuus L. and Sambucus glauca Nutt. These two plants were chosen because, having large leaves and trilacunar or multilacunar nodes, they strikingly contrast with Linum perenne which has small leaves and a single trace2 per leaf. MATERIAL AND METHODS.-The sunflower plants were raised in a greenhouse and the elderberry-was growing wild in the vicinity of Davis, California. Five shoots of Helianthus and one of Sambucus were sectioned transversely, several others longitudinally. Ordinary paraffin and staining methods were used in preparing the slides. Some of the prepared slides were kindly supplied by Dr. R. H. Wetmore of Harvard University. In the examination of the sections the same procedure was followed as that outlined in connection with similar studies on flax (Esau, 1942, 1943a). In all illustrations the leaves were numbered beginning with the youngest at the apex of the shoot. If the leaves were paired at the nodes, the two members of the pair received different numbers, though the two leaves were of the same age. Such numbering was convenient for the marking of the traces within the stem. To simplify the descriptions of the shoots, all leaves including the youngest, are spoken of as "leaves" and the terms "embryonic leaves" or "leaf primordia" are rarely employed. Heliaqnthus.-Table 1 characterizes the five sunflower plants used for detailed study. All were young plants and showed no evidence of a change from the vegetative to the reproductive stage of development. Column 2 in table 1 gives the numbers of foliage leaves in the five plants. Besides these leaves each I Received for publication September I2, 1944. 2 The term "trace" is applied throughout to each bundle which extends to a leaf. plant had two cotyledons. As Priestley and Scott (1936) have reported, Helianthus 'does not have a stable type of leaf arrangement. The first few leaves are more or less decussate' (fig. 2), later the phyllotaxis changes to some spiral system (fig. 9). Concomitant with this variability in leaf arrangement, the relation of the leaf traces to each other within the axial vascular skeleton shows no stable pattern. Each leaf usually has three traces, one larger, median and two smaller, lateral ones; occasionally there are more. (Leaf 15 of shoot 5 had four traces.) The apex of a Helianthus shoot in vegetative stage does not form a cone; instead, it has a flat surface and the newly forming leaves arise as mounds on the margins of this surface (fig. 1). The internodes associated with the youngest leaves do not elongate for a number of plastochrones so that several leaves at the apex are attached at close levels. The axis expands laterally just below the apical meristem and, in longitudinal sections, appears to form broad shoulders on either side of it. The uppermost leaves rest upon these shoulders (fig. 1). In transverse sections the stem apex occurs, even at its highest level, not as a separate entity but is continuous with a mass of tissue formed by the united bases of several leaves (fig. 3). The procambium was not studied in as much detail in the sunflower as in the flax (Esau, 1942) and the matter of the longitudinal course of procambial formation will not be commented upon in this paper. Procambial differentiation was usually evident in connection with leaves that were recognizable as small elevations above the apex; but no procambial strands were found that could have been interpreted as traces to future leaves whose primordia had not yet arisen. As in the flax (Esau, 1942), the procambium of the youngest organs is initiated through a series of longitudinal divisions. Figures 4 to 7 show the beginning of procambial differentiation in leaf 1 of the shoot depicted in figures 2 and 3; and figure 8 illustrates a portion of the procambial strand of

Linum perenne, spec. nov. 2. Linum calycibus capsulisque obtusis, foliis alternis lanceolatis integerrimis. Linum foliis alternis lanceolatis integerrimis, calycibus apice obtusis, capsulis muticis. Hort. ups.72. Linum perenne, ramis foliisque alternis lineari-lanceotis. Hort. cliff. 114. Roy. lugdb. 434. Sauv. monsp.53. Linum perenne majus caeruleum, capitulo majore. Moris. hist. 2. p.573. Linum sylvestre caeruleum perenne erectius, flore & capitulo majore. Raj. angl. 3. p.362. Habitat in Sibiria et Cantabrigiae . ���, Published as part of Linnaeus, Carolus, 1753, Species plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas, Stockholm :Laurentius Salvius on page 277, DOI: 10.5281/zenodo.3931989