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Orchid seeds usually have no endosperm; the seed coat embraces like a balloon the air-filled space between embryo and testa ( Limodorum abortivum ). – A: fluorescence microscopic image of L. abortivum – B: SEM image of L. abortivum : due to the high ac- celerating voltage of 30 keV (method after Wolter & Barthlott 1991) the embryo becomes clearly visible. 

Orchid seeds usually have no endosperm; the seed coat embraces like a balloon the air-filled space between embryo and testa ( Limodorum abortivum ). – A: fluorescence microscopic image of L. abortivum – B: SEM image of L. abortivum : due to the high ac- celerating voltage of 30 keV (method after Wolter & Barthlott 1991) the embryo becomes clearly visible. 

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The Orchidaceae with some 22 000 species is one of the two largest plant families. Despite of the vast literature on orchids, rather little is known about their seeds, which are generally considered as wind dispersed, small and reduced “dust seeds”. Based on some 1400 collections of orchid seeds analysed by SEM and other methods over the last four...

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... produce capsules (Fig. 1) and typi- cally form minute wind-dispersed seeds of only 0.1 -6 mm in size. They are characterized by a thin balloon-like seed coat and (in the major- ity of cases) the absence of endosperm (Fig. 2). The seed coat usually consists of uniform cells; seed coats that consist of different cell types oc- cur only in genera with very specialized seeds (see below). The embryo is much reduced and consists usually of only a few cells, though some species may contain more than one embryo per seed. Polyembryony with up to 12 embryos per seed ...
Context 2
... contrast to various aspects of flower morphology, micromorphological characters such as seed coats or pollen are usually barely influenced by environmental conditions. Orchids produce capsules (Fig. 1) and typically form minute wind-dispersed seeds of only 0.1 – 6 mm in size. They are characterized by a thin balloon-like seed coat and (in the major- ity of cases) the absence of endosperm (Fig. 2). The seed coat usually consists of uniform cells; seed coats that consist of different cell types oc- cur only in genera with very specialized seeds (see below). The embryo is much reduced and consists usually of only a few cells, though some species may contain more than one embryo per seed. Polyembryony with up to 12 embryos per seed (!) occurs in the seeds of Thecostele (Fig. 3). The structure of the orchid seed coat is rather conservative and supposed to be little prone to selective pressure since there is one predominant seed dispersal mechanism in the whole family. Orchids typically have tiny wind-dispersed seeds, often called “dust-seeds”. Most orchids are wind-dispersed, but there are exceptions and the dispersal mechanisms of orchids are more diverse than assumed earlier. A link of morphology and dispersal properties was already suggested by Arditti & al. (1980), and Healey & al. (1980) noted that “there is a functional correlation between orchid seed morphology, their wet- tability, and aerodynamics. These in turn affect the dispersion of the seeds”. A unique dispersal mechanism occurs in the Vanilloideae – Vanilleae : wind-dispersal by large sclerified winged seeds (Fig. 4). This type of anemochory is very different from the wind-dispersal of the tiny “dust-seeds” of the rest of the family. Cameron & Chase (1998) assume different dispersal mechanisms for the Vanilleae , including water dispersal for Epistephium and zoochory not in only Vanilla , but also Galeola . In addition to wind-dispersal, water-dispersal (hydrochory) could play a role in some species (Dressler 1981), e.g. in Epipactis gigantea ( Epi dendroideae – Neottieae ), a species often found growing next to streams. Hydrochory as the main dispersal mechanism has also been suggested for some species of Disa ( Orchidoideae – Dis eae ). The seeds of some Disa are very different compared to its related genera. They are unusu- ally large and also contain endosperm, which is unusual in orchids. This strikingly different morphology has also been noted by Kurzweil (1993). To explain this, Kurzweil discussed the habitats and dispersal modes of Disa uniflora , which occurs along the edges of perennial Western Cape streams where seeds must germinate quickly to prevent them being washed away by rain. Kurzweil therefore assumed that the Disa seed is adapted for that habitat: the endosperm allows a quick growth of the seedling. Some genera have large fruits with aromatic pulp and sclerified black seeds, both suggesting adaptations to zoochory. This is found mainly in the Vanilloideae (e.g. Vanilla , Erythrorchis and Pseudovanilla ). Sclerified seeds are also found in Apostasia Blume and Neuwiedia Blume ( Apostasioideae ), in Seleni pedium ( ...

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... The classification of Barthlott (1976), Barthlott and Ziegler (1981), Ziegler (1981), and Barthlott et al. (2014) identifies the Eulophia-type as the predominant seed type within the subtribe Malaxidinae. This type is distinguished by the presence of transverse sculptured thickenings on periclinal cell walls. ...
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Main conclusion During evolution, similar vectors of adaptive radiation may have evolved in the subtribe Malaxidinae. This was manifested in homologous series of variability in suspensor shape and seed coat ultrasculpture in clades of terrestrial and epiphytic orchids. Abstract The present study examines the variability of embryonic traits across clades and subclades of subtribe Malaxidinae (Orchidaceae), previously identified by molecular genetic data. Ovules and seeds from fruits of orchids of the genera Crepidium, Liparis (sections Cestichis and Blepharoglossum), Dienia, and Oberonia were examined by confocal laser microscopy with fluorescent dye staining. The branched or rounded suspensor in the studied species was unicellular and originated from the nondividing basal cell cb. The elongated or flattened transmission structure of one or two cells was located at the junction of the suspensor and the embryo proper. Two species (Oberonia gammiei and Liparis elliptica) were found to have unitegmal ovules. Three morphological groups of seeds were identified based on the shape and sculpture of the periclinal cell wall. A comparative analysis of the embryological characters in Malaxidinae species reveals that the lobed suspensor is a homoplasy present in different subclades of terrestrial and epiphytic orchids. The flat transmission cell is an apomorphy in the Cestichis subclade. Similarly, the independent formation of the unitegmal ovule occurred in two subclades of epiphytic orchids. The results of our study suggest that similar adaptive radiation vectors may have evolved in the subtribe Malaxidinae in the orchids we studied.
... Similar to what is observed in the crown, the presence of old leaf sheaths, maintaining a trough shape, generates satisfactory environmental conditions for the recruitment and development of epiphytes (Oliveira et al. 2015;Castro et al. 2016). Unlike V. palmarum, C. gardneri, as most orchids, has wind-dispersed dustlike seeds (Barthlott et al. 2014). Wind dispersal is less favorable in closed areas where wind speed tends to be lower (Givnish et al. 2005), such as in restinga forests. ...
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The Brazilian Atlantic Forest is home to more than 1,000 epiphytic orchid species. Palm trees are a conspicuous element in the Atlantic Coast restingas (environments characterized by high abiotic stress). We aimed to investigate whether orchids showed specificity for palm species and phorophyte strata (stem or crown) in a restinga area located in an Integral Protection Conservation Unit in Northeastern Brazil. We counted all palm trees ≥ 1.3 m in height and the epiphytic orchids found on them in four 1-ha plots established and distant from each other at least 100 m. Data were analyzed through ANOVA in a factorial scheme (2 × 2) and post hoc Tukey test to identify differences between means. We recorded 140 individuals of three orchid species growing on 75 individuals of two palm species. Catasetum gardneri and Vanilla palmarum were found exclusively as epiphytes on palm trees. Catasetum gardneri was exclusively associated with Syagrus schizophylla, whereas V. palmarum occurred predominantly on S. schizophylla, although it was also recorded on Elaeis guineensis (oil palm). The abundance of V. palmarum was not influenced by strata in E. guineensis. The stem and the crown of S. schizophylla were the most suitable strata for C. gardneri and V. palmarum, respectively. Our data reiterate that conserving palm trees, especially S. shyzophylla, is important for maintaining the populations of orchids and possibly other epiphytes.
... Orchids produce large numbers of wind-dispersed "dust" seeds per fruit [10] that lack endosperm and constitute little more than air-filled casings around the embryo. Orchid seeds exhibit extremely low germination rates because only a small portion of the large number of seeds will land on a suitable substrate and eventually germinate, and throughout their life cycle, orchid plants depend not only on the induction and symbiosis of specific fungal groups but also on stringent environmental conditions to support their normal growth [11,12]. In addition to these challenges, numerous species within this family are declining globally due to habitat loss, climate change, and shifts in species distributions pollinated by specific pollinators. ...
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Danxiaorchis yangii, a newly discovered fully mycoheterotrophic orchid. It relies on Lysimachia alfredii and Dufourea spp. for pollination, and environmental factors closely influence the growth and distribution of these pollinators, which in turn directly affects the growth and reproduction of D. yangii. Climate change threatens the suitable habitats for these three species, emphasizing the need to understand D. yangii’s response. This study comprehensively utilized the field distribution of D. yangii and related climatic data, along with future climate predictions from global models, to predict the climate suitability areas of D. yangii under two greenhouse gas emission scenarios (SSP245 and SSP370) using species distribution models (SDMs), which encompassed a random forest (RF) model. Additionally, we selected the optimal ensemble model (OEM) for Dufourea spp. and applied generalized boosted models (GBMs) and RF for L. alfredii in our predictions. The study found that precipitation of the driest quarter plays a pivotal role in determining the distribution of D. yangii, with an optimal range of 159 to 730 mm being most conducive to its growth. Comparative analysis further indicated that precipitation exerts a greater influence on D. yangii than temperature. Historically, D. yangii has been predominantly distributed across Jiangxi, Hunan, Zhejiang, and the Guangxi Zhuang Autonomous Region, with Jiangxi Province containing the largest area of highly suitable habitat, and this distribution largely overlaps with the suitable regions of its pollinators.
... Their survivability can be inferred by the ecological attributes of the UNIMAS campus and the morphological characteristics of the orchids with their surroundings. Seeds from species such as Dendrobium crumenatum, Spathoglottis plicata and Thrixspermum trichoglottis were observed to be small, orchid seeds reportedly ranging from 0.1 to 6.0 mm and resulting them to be lightweight that can be produced massively inside the seed pod (Barthlott et al., 2014). Likewise, they would easily be dispersed by wind and can remain airborne longer and further away which could facilitate seed distribution in developed areas (Jersakova & Malinova, 2007). ...
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For the past three decades, various biotic components in Universiti Malaysia Sarawak (UNIMAS) natural habitats have been studied but less attention given to the largest family of flowering plants, the Orchidaceae. A preliminary survey in the campus areas has resulted in the discovery of more than ten species of orchids. Therefore, in this study more field samplings were conducted throughout the UNIMAS campus focusing on the developed areas to unveil the potential of UNIMAS-developed areas as a growth ground for orchids. To date, 37 orchid species have been recorded from these areas; mainly found on the planted trees at the roadside and landscaped areas surrounding the academic buildings, while the terrestrial species were found to inhabit different types of disturbed habitat. Among them, Dendrobium pensile was identified as a new record to Sarawak while Dendrobium pseudostriatellum and Pinalia biglandulosa were endemic to Borneo. This study provides an insight into the orchid resiliency towards habitat alteration, landscape phorophytes species that can host orchids, and management of species in a developed landscape.
... As such, the millions of dust-like seeds can be easily uplifted and carried away by the wind. Nevertheless, there are a few notable exceptions [31,42,[45][46][47][48][49][50][51][52][53][54][55][56][57][58] (Table 1; Figure 1). Hydrochory, or the dispersal of seeds by water, is an extremely rare phenomenon that has been documented in only two species within the Epidendroideae subfamily, Disa uniflora P.J.Bergius [52,59] and Epipactis gigantea Dougl. ...
... Nevertheless, there are a few notable exceptions [31,42,[45][46][47][48][49][50][51][52][53][54][55][56][57][58] (Table 1; Figure 1). Hydrochory, or the dispersal of seeds by water, is an extremely rare phenomenon that has been documented in only two species within the Epidendroideae subfamily, Disa uniflora P.J.Bergius [52,59] and Epipactis gigantea Dougl. ex Hook. ...
... ex Hook. [52]. These species are typically found near waterbodies, and their fruit and seed traits differ from those of animal-dispersed orchids [52]. ...
Article
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Orchid seeds are predominantly wind-dispersed, often developed within dry, dehiscent fruits that typically release millions of dust-like seeds into the air. Animal-mediated seed dispersal is a lesser-known phenomenon in the family and predominantly occurs in groups belonging to early-diverging lineages bearing indehiscent, fleshy fruits with hard, rounded, dark seeds. In this review, we explore the evolutionary trends of seed dispersal mechanisms in Orchidaceae, focusing on the pantropical genus Vanilla. Notably, certain Neotropical species of Vanilla produce vanillin-aromatic compounds synthesized naturally in their fruits, which plays a pivotal role in seed dispersal. Ectozoochory occurs in dry, dehiscent fruits, whose seeds are dispersed by (i) male euglossine bees collecting the fruit's vanillin aromatic compounds and (ii) female stingless bees collecting the fruit's mesocarp. Endozoochory occurs in (iii) highly nutritious, indehiscent fruits consumed by terrestrial mammals or (iv) fleshy, dehiscent fruits whose mesocarp is consumed by arboreal mammals. Wind dispersal appears to be a derived state in Orchidaceae and, given its predominance, a trait likely associated with enhanced speciation rates. Zoochory primarily occurs in groups derived from early-diverging lineages; occasional reversions suggest a link between dispersal mode and fruit and seed traits. Interestingly, fruit dehiscence and fleshiness in Vanilla lack phylogenetic signal despite their role in determining dispersal modes, suggesting potential environmental adaptability.
... Limiting factors for the establishment and development of plants in stressful environments also include resource competition, which may counteract the effects of facilitation and result in population reductions or exclusion of community members (Callaway and Walker 1997). As a complicating factor, orchids usually have wind-dispersed seeds and without endosperm (Barthlott et al. 2014). Thus, germination only occurs when seeds fall on and germinate in suitable microsites containing specific mycorrhizal fungi that provide the necessary nutrients for orchids in their first stages of life (Zhao et al. 2021). ...
... Further, the significant positive correlation between the length and width of L. rigidus clumps and the number of young individuals or the total number of individuals of C. garneri in both areas corroborated our hypothesis. We based our hypothesis on the assumption that greater clumps of L. rigidus retain more seeds of C. gardneri, which are tiny and dispersed by wind over short distances (Chung et al. 2004;Barthlott et al. 2014). This ecological role played by L. rigidus is especially relevant in open costal environments, especially in shrubby restinga vegetation where relatively strong and incessant winds promote sand burial and thus pose an additional challenge to seedlings (Castanho et al. 2015). ...
Article
Catasetum gardneri is an ornamental orchid endemic to the Brazilian Atlantic Forest that occurs mainly as a terrestrial species in shrubby restinga vegetation, within thicket clumps of Lagenocarpus rigidus (Cyperaceae). We investigated the interspe-cific relationship between these species and evaluated the abundance and structure of two subpopulations of C. gardneri in two hectares of a fragment of restinga in Bahia State. We found 167 individuals of C. gardneri (104 juveniles and 63 adults) in 3098 thickets of L. rigidus. The abundance of C. gardneri was higher inside the thicket clumps of L. rigidus, specially the larger ones, than on bare sand (n = 65) and on isolated host plants (n = 7). We concluded that L. rigidus may act as a nurse plant, facilitating the establishment of C. gardneri. Facilitation by L. rigidus would be related to its leaves-since when dry, they curl up and remain attached to the plant-and leaf sheaths that accumulate on the caudex. These structures likely contribute to minimize abiotic stresses and alter the local availability of resources. These discoveries open new lines of investigation and reveal the possibility of using L. rigidus in population reinforcement, reintroduction or even ex situ cultivation of C. gardneri.
... Arditti and Ghani (2000) detailed the numerical and physical characteristics of orchid seeds in an extensive review. Barthlott et al. (2014) provided a scanning electron microscopy survey of orchid seed diversity, illustrating the seed coat's surface features and morphology. ...
Article
Full-text available
Orchid seeds are 'dust-like.' The seed coat is usually thin, with only one to a few cell layers. It originates from the integuments formed during ovule development. In orchids, the outer integument is primarily responsible for forming a mature seed coat. The inner integument usually fails to develop after fertilization, becomes compressed, and collapses over the expanding embryo. Hence, the seed coat is formed from the funiculus, chalaza, and outer integumentary cells. The outermost layer of the seed coat, the testa, is lignified, usually at the radial and inner tangential walls. The subepidermal thin-walled layer(s), the tegmen, subsequently cold, resulting in seeds having only a single layer of seed coat cells. In some species, cells of the inner integument remain alive with the ability to synthesize and accumulate lipidic and or phenolic compounds in their walls covering the embryo. This cover is called the 'carapace,' a protective shield contributing to the embryo's added protection. A developmental and functional perspective of the integuments and seed coat during seed development and germination is presented in this review. Supplementary Information The online version contains supplementary material available at 10.1186/s40529-023-00400-0.
... Seed morphology is associated with important processes such as seed dispersal, dormancy, germination, and establishment, which are all relevant to seed conservation [15]. Seed traits are thought to be more conservative than floral and vegetative characteristics, and consequently they are also valuable indicators of the taxonomy, phylogenetics, and phytogeographic distribution of orchid species [16,17]. ...
... Most orchid seeds are small (dust-like), with a low weight. A single capsule (the reproductive unit) can produce thousands of seeds [17]. Due to their minuscule size, seed characteristics remain undescribed for many orchid species. ...
... Due to their minuscule size, seed characteristics remain undescribed for many orchid species. Orchid seeds typically consist of a seed coat that incorporates an embryo and an internal air space volume (between the seed coat and embryo), lacking an endosperm [17]. ...
Article
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Neotropical orchids are vulnerable to extinction due to overharvesting, habitat destruction and climate change. However, a basic understanding of orchid seed biology to support conservation efforts is still lacking for most species. Seed morphology is linked to plant adaptation and evolution, influencing seed dispersal, dormancy, longevity, and germination, which are valuable traits for conservation. In this study, we characterized and compared the morphological traits of seed capsules (size, shape, and colour) and seeds (seed and embryo shape and size and internal airspace volume) for three epiphytic Neotropical orchid species of the genus Lycaste native to Guatemala: L. cochleata, L. lasioglossa, and L. virginalis. The three species show qualitative similarities in seed capsule colour and appearance and in seed morphology (i.e., scobiform oval-shaped seeds and prolate-spheroid embryos). All species have small-sized seeds (length of L. cochleata: 210 µm, L. lasioglossa: 230 µm, and L. virginalis: 260 µm), with proportionally large embryos (length of L. cochleata: 140 µm, L. lasioglossa: 120 µm, and L. virginalis: 150 µm) and an internal airspace volume that occupies less than half of the seed (L. cochleata: 17%, L. lasioglossa: 42%, and L. virginalis: 30%). This finding is consistent with previous reports for other epiphytic orchid species, which typically have lower air volumes than terrestrial orchids. These differences are likely a result of evolutionary changes associated with different habits and may influence seed dispersal. We also found some significant differences in seed morphology between the studied species, but their taxonomic, biological, and ecological relevance remain to be elucidated. More comparative studies, including on other Lycaste species with different habits, are needed to explore relationships between seed morphology, taxonomy, biology, and ecology in this genus to support its conservation.
... Orchidaceae represents one of the most diverse families of flowering plants, consisting of about 35 000 species, which have fascinated botanists and plant enthusiasts over centuries (Barthlott et al., 2014), due to its extensive horticultural, medicinal, and culinary uses. The Cattleya genus is one of the most popular and widely cultivated in this family; the high ornamental value of its members and large ability for genetic recombination are attractive to the market (Galdiano et al., 2017). ...
... Seed morphology: Considering the five seed size categories established by Barthlott et al. (2014) (Very small 100-200 µm; small 200-500 µm; medium 500-900 µm; large 900-2 000 µm; and very large 2 000-6 000 µm), our data indicate that C. crispa has medium-sized seeds. This category includes the seeds most found in the Orchidaceae family (Barthlott et al., 2014). ...
... Seed morphology: Considering the five seed size categories established by Barthlott et al. (2014) (Very small 100-200 µm; small 200-500 µm; medium 500-900 µm; large 900-2 000 µm; and very large 2 000-6 000 µm), our data indicate that C. crispa has medium-sized seeds. This category includes the seeds most found in the Orchidaceae family (Barthlott et al., 2014). 100 µm (C., G., I.). 2 µm (B., D., J.). 1 µm (F., H.). ...
Article
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Introduction: Cattleya crispa is an ornamental epiphytic orchid with geographic distribution restricted to the Brazilian Atlantic Forest. Due to predatory extractivism and human-induced habitat loss, this species appears on the Red List of Brazilian Flora. Objective: To characterize morpho-anatomical aspects regarding germination and post-seminal development from C. crispa seeds; as well as studying the effect of cryopreservation on these seeds. Methods: We used light microscopy and electron microscopy to describe the microstructure of a 100 ripe seeds. We evaluated seed viability, seed germination, survival rate and protocorm weight in cryopreserved and non-cryopreserved material, with four replicas per treatment using 20 mg of plant material. Results: The seeds are fusiform, whitish yellow with a length from 700 to 900 µm and a water content of 5 %. Germination began seven days after sowing, the formation of the globular protocorm at 30 days and the formation of the seedling occurred 150 days. The persistent seed coat can compress the protocorm and cause it to collapse. The cryopreserved seeds presented 87.15 % viability, 78.32 % germination, 8.48 % survival and protocorms with 104.27 mg five months after sowing. Data wasn't different to non-cryopreserved seeds. Conclusions: The cryocapability of the seeds shows that cryopreservation can be used for long-term conservation. The results of this work contribute to the overall biology of C. crispa and to the propagation and storage of genetic material for conservation purposes.
... Terrestrial orchids produce numerous dust-like seed, with a single capsule containing between 0.2 to 2 million seed (Barthlott et al., 2014). However, in the wild, only a small proportion of seed can be successfully germinated. ...
... Imaging was done using a FESEM Mira 3 microscope (Tescan, Breno, Czech Republic) (30 kV voltage) to study seed testa morphometric features. The method and terminology proposed by Barthlott et al. (2014) was used. Three replications of seed capsules were examined, and within each replication, five seeds were randomly selected for assessment. ...
Article
We aimed to explore in vitro seed germination optimizing and somatic embryogenesis induction as well as to identify phytochemical constituents of endangered terrestrial orchid, Dactylorhiza umbrosa (Kar. & Kir.) Nev-ski. The highest germination rate (93.04 §0.90%) was achieved with the combination of pineapple juice (PJ) and casein hydrolysate (CH). Moreover, the individual application of organic nitrogen compounds (Vamin, peptone, and casein hydrolysate) led to the higher germination efficiencies, with Pep being the most effective in shortening the germination time (the number of days from seed sown to embryo enlargement and seed testa rupture) (2.9 times faster compared to PJ+Pep+CH). Young protocorm explants treated with 1 mg L À 1 2,4-D and 2 mg L À 1 Kin showed the highest embryogenesis rate (39.99 §5.72%), while this explant treated with 0.5 mg L À 1 2,4-D and 2 mg L À 1 Kin produced the highest embryo number (5.37 §0.21). Morpholine, 4-(4-methyl-1-cyclohexen-1-yl) was the predominant phytochemical in tuber methanolic extract (60.63 § 3.23%), while 1,2,3-propanetriol was found at the highest percentage in leaf methanolic extract (47.48 § 3.23%). The extracts derived from the tubers had more content of total phenolics (TP) and total flavonoids (TF), as well as a greater antioxidant activity (TAA) compared to the extract obtained from the leaves. The recorded glucomannan content (31.31 §0.60%) was lower than that of starch (32.65 §1.22%), however both carbohydrates were responsible for the recorded viscosities of Salep samples. Due to high viscosity of products from Salep powder obtained from D. umbrosa, its tubers are used as superior crude materials in Iranian herbal markets. Taking into account the endangered status of D. umbrosa populations in the Euro-Mediterra-nean and the Middle East basins caused by climate change and human activities, our method may be exploited for large-scale propagation of in vitro raised plants and reintroduce them into their natural habitats.