Archaeobotanical finds of plant parts, especially of wild taxa that were domesticated and their derived domesticated forms, unearthed from archeological sites assume an important role in plant domestication research. Those finds are used in modelling plant domestication under the explicit or implicit assumptions that they represent past genetic, ecological, and cultural situations and dynamics and may illuminate the mechanisms that underly plant domestication. This 'representability assumption' is discussed herein by considering the potential contribution to the archaeobotanical finds of a source that was not investigated in depth in the past - that is, 'housetop plants'. The match between the lists from four botanically surveyed ruins in Israel, taxa mentioned in the archaeobotanical literature, and lists of segetal taxa in recent traditional argo-ecologies in Israel, shows that flora of housetop and ruins of built complexes should be considered as an important origin of archaeobotanical finds identified in archaeological sites. These results are further considered on the backdrop of the suggested protracted model of plant domestication in the Levant focusing on pre-domestication cultivation and arguments concerning weeds of cultivation.

Fiber-like cells with thickened cell walls of specific structure and polymer composition that includes (1 → 4)-β-galactans develop in the outer stem cortex of several moss species gametophytes. The early land plants evolved several specialized cell types and tissues that did not exist in their aquatic ancestors. Of these, water-conducting elements and reproductive organs have received most of the research attention. The evolution of tissues specialized to fulfill a mechanical function is by far less studied despite their wide distribution in land plants. For vascular plants following a homoiohydric trajectory, the evolutionary emergence of mechanical tissues is mainly discussed starting with the fern-like plants with their hypodermal sterome or sclerified fibers that have xylan and lignin-based cell walls. However, mechanical challenges were also faced by bryophytes, which lack lignified cell-walls. To characterize mechanical tissues in the bryophyte lineage, following a poikilohydric trajectory, we used six wild moss species (Polytrichum juniperinum, Dicranum sp., Rhodobryum roseum, Eurhynchiadelphus sp., Climacium dendroides, and Hylocomium splendens) and analyzed the structure and composition of their cell walls. In all of them, the outer stem cortex of the leafy gametophytic generation had fiber-like cells with a thickened but non-lignified cell wall. Such cells have a spindle-like shape with pointed tips. The additional thick cell wall layer in those fiber-like cells is composed of sublayers with structural evidence for different cellulose microfibril orientation, and with specific polymer composition that includes (1 → 4)-β-galactans. Thus, the basic cellular characters of the cells that provide mechanical support in vascular plant taxa (elongated cell shape, location at the periphery of a primary organ, the thickened cell wall and its peculiar composition and structure) also exist in mosses.

Indented growth rings were found long ago to be experimentally induced in Pinus halepensis Miller by thin parallel axial scratching of the bark up to the vascular cambium with a sharp blade. Here, we show that when the bark and vascular cambium of P. halepensis are wounded by wide and long parallel axial wounds (“windows”) rather than by thin scratches, the induced indented growth rings become dramatically more indented. All ten trees that were wounded by long parallel “windows” responded with very strong growth (especially in the first two years) that resulted in the formation of very conspicuous, extremely indented growth rings in the wood formed in between the long and wide woundings. This is true for both the trunks that were wounded all around their circumference and those that were wounded only in part of their circumference. We also suggest further lines of research.

Functional biogeography is the discipline that studies the geographic distribution of organismal traits and their relationships with environmental conditions and ecosystem functioning. Trait multifunctionality can be a major challenge in such analyses, so deciphering trait geographic distributions from functions is not always straightforward. We studied spinescence in the flora of Israel and the Palestinian Authority as a case of a multifunctional trait, associated mainly with antiherbivory defence, aridity alleviation, and propagule and seed dispersal. We studied how the proportion of spiny species in the flora of Israel and the Palestinian Authority and the distribution of different spine locations within the plants vary along a very strong bioclimatic (especially rainfall) gradient in Israel and the Palestinian Authority. We found that plant spinescence, as expressed in species proportion, is more frequently positively associated with increasing aridity and summer heat, and more generally with resource limitations. However, spinescence of reproductive plant parts, which in many species aids seed dispersal, presents opposite trends. These patterns reflect the differing importance of each of the three major roles attributed to plant spinescence, and point to the relative importance of each in driving overall spinescence geographic distribution. Thus, the traits’ geographic distribution patterns can elucidate these traits’ multifunctionality and improve our understanding of the evolution and spatial variation among these functions.

Floral bracts (bracteoles, cataphylls) are leaf-like organs that subtend flowers or inflorescences but are of non-floral origin; they occur in a wide diversity of species, representing multiple independent origins, and exhibit great variation in form and function. Although much attention has been paid to bracts over the past 150 years, our understanding of their adaptive significance remains remarkably incomplete. This is because most studies of bract function and evolution focus on only one or a few selective factors. It is widely recognised that bracts experience selection mediated by pollinators, particularly for enhancing pollinator attraction through strong visual, olfactory, or echo-acoustic contrast with the background and through signalling the presence of pollinator rewards, either honestly (providing rewards for pollinators), or deceptively (attraction without reward or even trapping pollinators). However, studies in recent decades have demonstrated that bract evolution is also affected by agents other than pollinators. Bracts can protect flowers, fruits, or seeds from herbivores by displaying warning signals, camouflaging conspicuous reproductive organs, or by providing physical barriers or toxic chemicals. Reviews of published studies show that bracts can also promote seed dispersal and ameliorate the effects of abiotic stressors, such as low temperature, strong ultraviolet radiation, heavy rain, drought, and/or mechanical abrasion, on reproductive organs or for the plants' pollinators. In addition, green bracts and greening of colourful bracts after pollination promote photosynthetic activity, providing substantial carbon (photosynthates) for fruit or seed development, especially late in a plant's life cycle or season, when leaves have started to senesce. A further layer of complexity derives from the fact that the agents of selection driving the evolution of bracts vary between species and even between different developmental stages within a species, and selection by one agent can be reinforced or opposed by other agents. In summary, our survey of the literature reveals that bracts are multifunctional and subject to multiple agents of selection. To understand fully the functional and evolutionary significance of bracts, it is necessary to consider multiple selection agents throughout the life of the plant, using integrative approaches to data collection and analysis.

Glandular trichomes are traditionally regarded as a defence against insect herbivores in plants. A comprehensive examination of their occurrence across an entire flora is essential for understanding how plant-herbivore interactions influence species abundance, traits, and diversity. In this study, we gathered data on the presence of glandular trichomes in a diverse flora comprising 7751 angiosperm species from the Hengduan Mountains region in southwestern China, testing the effects of plant organ, life form, leaf habit, phylogenetic position, and geographical element on the occurrence of glandular trichomes. Our results showed that 1021 species (13.2%) in the studied flora possessed glandular trichomes. Reproductive organs (88.0%) displayed a significantly higher occurrence of glandular trichomes compared to vegetative organs (59.1%). Within flowers, the calyx (81.1%) was the most defended, followed by the corolla (17.4%), and the gynoecium (12.5%). The androecium (1.8%) was the flower component least associated with glandular trichomes. Herbaceous species (14.0%) were more likely to have glandular trichomes than woody species (11.6%). For woody plants, leaf habit (deciduous/evergreen) had no significant effect on the presence of glandular trichomes on leaf blades, but had a significant effect on the occurrence of glandular trichomes on reproductive organs, with deciduous woody species (11.0%) displaying a higher prevalence compared to evergreen woody species (8.3%). Interestingly, the proportion of species with glandular trichomes was notably lower in the tropical elements (6.8%) compared to both temperate and cosmopolitan elements (15.3% and 15.6%, respectively). Our findings suggest that in the Hengduan Mountains region, the evolution of glandular trichomes exhibits distinct patterns among various life forms, plant organs, leaf habits, and geographical elements, while showing limited influence from phylogenetic relatedness, highlighting the remarkable evolutionary adaptability of this defensive plant trait.

Florivory, i.e., flower herbivory, of various types is common and can strongly reduce plant fitness. Flowers suffer two very different types of herbivory: (1) the classic herbivory of consuming tissues and (2) nectar theft. Unlike the non-reversibility of consumed tissues, nectar theft, while potentially reducing a plant’s fitness by lowering its attraction to pollinators, can, in various cases, be fixed quickly by the production of additional nectar. Therefore, various mechanisms to avoid or reduce florivory have evolved. Here, I focus on one of the flowers’ defensive mechanisms, aposematism, i.e., warning signaling to avoid or at least reduce herbivory via the repelling of herbivores. While plant aposematism of various types was almost ignored until the year 2000, it is a common anti-herbivory defense mechanism in many plant taxa, operating visually, olfactorily, and, in the case of nectar, via a bitter taste. Flower aposematism has received only very little focused attention as such, and many of the relevant publications that actually demonstrated herbivore repellence and avoidance learning following flower signaling did not refer to repellence as aposematism. Here, I review what is known concerning visual-, olfactory-, and nectar-taste-based flower aposematism, including some relevant cases of mimicry, and suggest some lines for future research.

The identification and interpretation of wood remains from archaeological contexts is a well-established discipline with its own theoretical principles and methodologies within the research fields of archaeobotany, environmental archaeology and palaeoecology. Wood was an essential material in the ancient world, as it was used for virtually all aspects of daily life (including fuel, construction and artifact manufacturing) while simultaneously being symbolically charged and at times even serving as a status marker. In this entry, we describe the biological and technical aspects of the identification of archaeological wood remains (mainly charred, dry, and waterlogged) based on their anatomical structure. Methods for field sampling, microscopic analysis and data interpretation are also discussed.

Thermogenesis - the ability to generate metabolic heat - is much more common in animals than in plants, but it has been documented in several plant families, most prominently the Araceae. Metabolic heat is produced in floral organs during the flowering time (anthesis), with the hypothesised primary functions being to increase scent volatilisation for pollinator attraction, and/or to provide a heat reward for invertebrate pollinators. Despite in-depth studies on the thermogenesis of single species, no attempts have yet been made to examine plant thermogenesis across an entire clade. Here, we apply time-series clustering algorithms to 119 measurements of the full thermogenic patterns in inflorescences of 80 Amorphophallus species. We infer a new time-calibrated phylogeny of this genus and use phylogenetic comparative methods to investigate the evolutionary determinants of thermogenesis. We find striking phenotypic variation across the phylogeny, with heat production in multiple clades reaching up to 15°C, and in one case 21.7°C above ambient temperature. Our results show that the thermogenic capacity is phylogenetically conserved and is also associated with inflorescence thickness. Our study paves the way for further investigations of the eco-evolutionary benefits of thermogenesis in plants.

A recent important paper (Ide, Arthropod-Plant Interact 16:567–581, 2022) reported the experimental testing of two (out of several) of the visual red young leaf anti-herbivory hypotheses: (1) Aposematism by red young leaves; (2) Undermining herbivorous insect camouflage. Ide (Arthropod-Plant Interact 16:567–581, 2022) interpreted his solid experimental results as supporting the aposematic red leaf defence hypothesis, but not supporting the undermining herbivorous insect camouflage. I wish to clarify that because the undermining herbivorous insect camouflage hypothesis has two components: (1) Herbivores refrain from occupying colourful surfaces that do not match their colour; (2) If and when not refraining from occupying them, they are exposed to higher predation and parasitism risks. Thus, Ide’s (Arthropod-Plant Interact 16:567–581, 2022) results seem to support both hypotheses, and not only aposematism. Accordingly, Ide’s (Arthropod-Plant Interact 16:567–581, 2022) results do support the undermining herbivorous insect camouflage hypothesis, especially by exposing the insects that do not refrain from occupying leaves that do not match their colour to higher predation risks.

The bark fulfils several essential functions in vascular plants and yields a wealth of raw materials, but the understanding of bark structure and function strongly lags behind our knowledge with respect to other plant tissues. The recent technological advances in sampling and preparation of barks for anatomical studies, along with the establishment of an agreed bark terminology, paved the way for more bark anatomical research. Whilst datasets reveal bark’s taxonomic and functional diversity in various ecosystems, a better understanding of the bark can advance the understanding of plants’ physiological and environmental challenges and solutions. We propose a set of priorities for understanding and further developing bark anatomical studies, including periderm structure in woody plants, phloem phenology, methods in bark anatomy research, bark functional ecology, relationships between bark macroscopic appearance, and its microscopic structure and discuss how to achieve these ambitious goals.

The occurrence of indented growth-rings, commonly known as hazel wood, is rare in nature and the biology of its formation has not been studied much. Here, we review the current understanding and update on the issue of indented growth-rings formation in trees. We propose distinguishing between internally induced indented growth-rings, and externally induced ones as the outcome of cambial wounding (following fires, rockfall, various human activities, by insects, mammalian herbivores, and pathogens). Indented growth-rings are known to be endogenously induced by genetically-based imbalances in the hormonal regulation in the cambial zone in Karelian birch, and because of unknown reasons in Cryptomeria japonica. In some Pinus species it can be induced artificially by longitudinal (axial) parallel scratches of the active cambium with sharp razors. Indented growth-rings display remarkable aesthetic properties, and also may possess superior acoustic characteristics when used for constructing musical string instruments. Deeper understanding of indented growth-rings' formation mechanisms is needed in order to exploit the possibility of its regular artificial induction by cambial wounding or via tree breeding for potential commercial and scientific purposes.

Avoiding attacks is clearly better than suffering, or even overcoming attacks. Here we discuss the signalling ways by which galls (i.e., gall-inducers) may defend themselves from damage by avoiding attacks. Many colourful galls that are simultaneously chemically and/or physically defended, and/or omit repelling odours fulfilling the general criteria to be tentatively considered as aposematic. It has been shown experimentally that chemically defended galls also emit volatiles that repel relevant herbivores. Thus, both visual and olfactory gall traits may serve as adaptive signals that have been usually overlooked. It is also highly probable that the conspicuous colours (red, yellow) of many galls may also serve physiological functions, such as defence from reactive-oxygen production, from UV, and from excess visible light, or serve other, unknown functions. The certain role of camouflage (especially by being green), in defence from enemies, thus potentially increasing a gall-inducers’ fitness, was not given the attention it deserves. Detailed comparative and especially experimental studies on the adaptive role of gall shape, colouration and odours can further shed light on these phenomena.

Yellow and red autumn leaves are typical of many temperate/boreal woody plants. Since the 19(th) century, it has been either considered the non-functional outcome of chlorophyll degradation that unmasks the pre-existing yellow and red pigments or that the de novo synthesis of red anthocyanins in autumn leaves indicated that it should have a physiological function, although it was commonly ignored. Defending free amino acids and various other resources released especially following the breakdown of the photosynthetic system, and mobilizing them for storage in other organs before leaf fall, is the cornerstone of both the physiological and anti-herbivory hypotheses about the functions of yellow and red autumn leaf colouration. The complicated phenomenon of conspicuous autumn leaf colouration has received significant attention since the year 2000, especially because ecologists started paying attention to its anti-herbivory potential. The obvious imperfection of the hypotheses put forth in several papers stimulated many other scientists. Hot debates among physiologists, among ecologists, and between physiologists and ecologists have been common since the year 2000, first because the various functions of yellow and red autumn leaf colouration are non-exclusive, and second because many scientists were trained to focus on a single subject. Here, I will review the debates, especially between the photoprotective and the anti-herbivory hypotheses, and describe both the progress in their understanding and the required progress.

Some plant lineages, such as Araceae and Orchidaceae, have independently evolved deceptive flowers. These exploit the insect's perception and deceive the insects into believing to have located a suitable opportunity for reproduction. The scent compounds emitted by the flowers are the key signals that dupe the insects, guiding them to the right spots that in turn ensure flower pollination. Most species of the genus Amorphophallus of the Araceae emit scent compounds that are characteristic of a deceit, suggesting a specific plant pollinator interaction and according odors. However, only a few clear evolutionary trends in regard to inflorescence odors in Amorphophallus could be traced in previous studies - an intriguing result, considered the multitude of characteristic scent compounds expressed in Amorphophallus as well as the key function of scent compounds in deceptive floral systems in general. At least two factors could account for this result. (1) The deceptive pollinator-attraction floral system, including the emitted scent compounds, is less specific than assumed. (2) An evolutionary trend cannot be discerned if the intraspecific scent variation (odor polymorphism) exceeds the interspecific odor variation. Therefore, we discuss the potential deceptive function of the emitted scent compounds, in particular those that are related to cadaveric decomposition. Moreover, we review the data about emitted scent compounds in Amorphophallus with a focus on putative odor polymorphism. Upon examination, it appears that the emitted scent compounds in Amorphophallus are highly mimetic of decomposing organic materials. We show that several species display odor polymorphism, which in turn might constitute an obstacle in the analysis of evolutionary trends. An important odor polymorphism is also indicated by subjective odor perceptions. Odor polymorphism may serve several purposes: it might represent an adaptation to local pollinators or it might assumingly prevent insects from learning to distinguish between a real decomposing substrate and an oviposition-site mimic.

Clonal plants present an interesting example of division of labour among their ramets. Here we elaborated on hydraulic structure in respect to the division of labour among ramets in Arundo donax, a perennial clonal reed. Mature clones have three shoot types: (1) large mostly flowering; (2) medium mostly vegetative and (3) small vegetative. The shoots grow from buds initiating in the upper side of underground rhizomes, and the shoot growth is primary with vasculature produced from the procambium. We tested whether the number of vascular strands in a shoot has a fixed developmental programme or follows a flexible developmental pattern, and we found that the number of vascular strands strongly differs between shoot types. Large shoots on average have 560 vascular strands with both the widest vessels and significantly highest hydraulic conductivity. Medium ones and small shoots have 409 and 102 on average, respectively, with narrower vessels and with low conductivity. Thus, the shoot apices have three alternative developmental programmes. Apparently, a clone is built of functionally different modular units that enable Arundo donax to maximize its potential in a heterogeneous environment. Although the smaller culms do not contribute directly to the sexual reproduction of the clone, under stress their safer hydraulic system offers them a better chance of survival.

Glandular trichomes are well known to participate in plant chemical and physical defenses against herbivores, especially herbivorous insects. However, little is known about large-scale geographical patterns in glandular trichome occurrence. Herbivory pressure is thought to be higher at low elevations because of warmer and more stable climates. We therefore predicted a higher proportion of species with glandular trichomes at low elevations than at higher elevations. We compiled glandular trichome data (presence/absence) for 6,262 angiosperm species from the Hengduan Mountains (a global biodiversity hotspot in southwest China). We tested the elevational gradient (800-5,000 m a.s.l.) in the occurrence of plant species with glandular trichomes, and its correlations with biotic (occurrence of herbivorous insects) and abiotic factors, potentially shaping the elevational gradient in the occurrence of glandular trichomes. We found a significantly positive relationship between elevation and the occurrence of glandular trichomes, with the proportion of species having glandular trichomes increasing from 11.89% at 800 m a.s.l. to 17.92% at above 4,700 m. This cross-species relationship remained significant after accounting for phylogenetic relationships between species. Herbivorous insect richness peaked at mid-elevations and its association with the incidence of glandular trichomes was weak. Mean annual temperature was the most important factor associated negatively with glandular trichomes. Our results do not support the hypothesis that plant defenses decrease with increasing elevation. In contrast, a higher proportion of plant species with glandular trichome toward higher elevations is observed. Our results also highlight the importance of considering the simultaneous influences of biotic and abiotic factors in testing geographical variation in multifunctional plant defenses.

A “cultivation prior to domestication”, or a “pre-domestication cultivation” phase features in many reconstructions of Near Eastern plant domestication. Archaeobotanists who accept this notion search for evidence to support the assumption regarding a wild plant’s cultivation phase, which in their view, preceded and eventually led to plant domestication. The presence of non-crop plant remains in the archaeobotanical record interpreted as arable weeds, i.e., weeds of cultivation, is viewed as a strong argument in support of the pre-domestication cultivation phase. Herein, we show that the simple practice of harvest by hand-pulling (uprooting) has the potential to secure an almost weed-free harvest. Indeed, rather clean (weed-free) Neolithic seed caches from a range of relevant sites were documented in archaeobotanical reports. These reports, alongside ethnographic observations suggest that (in certain cases) ancient harvest may have been carried out by selective hand-pulling. Hence, one has no reason to view archaeobotanical assemblages from occupation sites as fully representative of cultivated fields. Therefore, the concept of “arable—pre-domestication weeds”, its logic, and its potential contribution to the prevailing reconstructions of Near Eastern plant domestication need be reconsidered.

A common idea is that resisting or blocking herbivore attacks by structural, chemical and molecular means after they have commenced is the first line of plant defence. However, these are all secondary defences, operating only when all the various methods of avoiding attack have failed. The real first line of plant defence from herbivory and herbivore-transmitted pathogens is avoiding such attacks altogether. Several visual, chemical and 'statistical' methods (and commonly their combined effects) have been proposed to allow avoidance of herbivore attacks. The visual types are camouflage, masquerade, aposematic coloration of toxic or physically defended plants (including Mullerian/Batesian mimicry), undermining herbivorous insect camouflage, delayed greening, dazzle and trickery coloration, heterophylly that undermines host identification, leaf movements, and signalling that colourful autumn leaves are soon to be shed. The mimicry types include: herbivore damage, insects and other animals, fungal infestation, dead/dry leaves or branches, animal droppings, and stones and soil. Olfactory-based tactics include odour aposematism by poisonous plants, various repelling volatiles, mimicry of faeces and carrion odours, and mimicry of aphid alarm pheromones. The 'statistical' methods are mast fruiting, flowering only once in many years and being rare. In addition to the theoretical aspects, understanding these mechanisms may have considerable potential for agricultural or forestry applications.

We present here the earliest evidence for large-scale table olive production from the mid-7 th millennium BP inundated site of Hishuley Carmel on the northern Mediterranean coast of Israel. Olive pit size and fragmentation patterns, pollen as well as the architecture of installations associated with pits from this site, were compared to finds from the nearby and slightly earlier submerged Kfar Samir site. Results indicate that at Kfar Samir olive oil was extracted, while at Hishuley Carmel the data showed that large quantities of table olives, the oldest reported to date, were prepared. This process was most probably facilitated by the site’s proximity to the Mediterranean Sea, which served as a source of both sea water and salt required for debittering/pickling/salting the fruit, as experimentally demonstrated in this study. Comparison of pit morphometry from modern cultivars, wild-growing trees and the archaeological sites, intimates that in pit morphology the ancient pits resemble wild olives, but we cannot totally exclude the possibility that they derive from early cultivated trees. Our findings demonstrate that in this region, olive oil production may have predated table olive preparation, with each development serving as a milestone in the early exploitation of the olive.