Preface

Most vascular plants are autotrophic, producing their food through photosynthesis. However, a significant number of plants have adopted a heterotrophic mode of life, obtaining part, or all of their requirements from other organisms. This group of heterotrophic plants includes **parasitic plants**, which grow on other plants and establish an organic union or haustorium through which they obtain food directly from the host. Parasitic plants can be broadly categorized into two groups based on their modes of nutrition: **hemiparasites and holoparasites**. The former possess chlorophyll and are capable of photosynthesis (at least during some phase of their cycle) and they obtain only water and mineral salts through haustoria with the host. The most extreme manifestation of parasitism occurs in holoparasites, which are totally achlorophyllous, obtaining all their nutrients from the host, on which they are totally dependent. Most holoparasites are found parasitizing the roots of their hosts.

Parasitic plants are among the most problematic pests of agricultural crops worldwide. About 4000 parasitic plants exploit another plant vascular system to fulfill their nutrient requirements. In his chapter, "*Parasitic Plants in Agriculture and Management*," Pervin Erdogan reviews these fascinating plants. Parasitic weeds are difficult to control because there are few resources for crop resistance and it is difficult to apply sufficiently selective control methods to kill weeds without physically and biochemically damaging the crop to which they are attached. The author specifically introduces plants such as mistletoe (*Viscum album* L.), *Cuscuta* spp., *Orobanche* spp., and the witchweeds (*Striga* spp.), providing information on their management and control.

"*Parasitic Plants as Vectors for Pathogens*" by Anupam Gogoi et al. discusses the various modes of parasitism and the nutrition of parasitic plants. In addition, the authors describe the mechanism of transmission of various pathogens by parasitic plants (including viruses, phytoplasmas, and proteobacteria) in host plants by *Cuscuta* species.

As mentioned, some of the representatives of these specialized plants represent great losses for agriculture, while others are threatened for various reasons, in addition to having uses and applications for humans. "*Aspects of the Biology and Ethnobotany of Parasitic Angiosperm Species in Nigeria*" by Odoligie Imarhiagbe examines the Nigerian environment, which has heterogeneous vegetation, traversing mangroves, rainforest, and savannah vegetation. It is home to host parasitic plant species, including endemic, native, and exotic species. This chapter gathers and synthesizes available information regarding parasitic plants in Nigeria, particularly their biology and the host species supporting their population.

In "*Anatomy, Embryology and Life Cycle of* Lophophytum*, a Root-Holoparasitic Plant,*" Sato and Gonzalez summarize the entire knowledge of the genus *Lophophytum*, focusing on its life cycle and the anatomy and histology of two species: *L. leandri*  and *L. mirabile.* Among the topics discussed are morphology and anatomy of the vegetative body, including the host/parasite interphase; structure, anatomy, and

ontogeny of unisexual flowers; description of embryological processes, from gamete formation; morphology and anatomy of fruit and seed; taxonomic value of floral characteristics; observations on dissemination, germination, and the establishment of the parasitic relationship with the host; the evolutionary trend in the gynoecium and embryo sac of the Balanophoraceae; and synchronization of parasite and host life cycles.

Alfalfa (*Medicago sativa* L.) is recognized as one of the most important forage crops in the world. In "*Parasitic Plants in Forage Legumes –* Medicago sativa *L.,*" Rozafa Fetahaj et al. present the problem of parasitic plants for this plant species. Weeds, as the most problematic pests in agriculture, compete with crops for water, nutrients, light, and space, constituting a threat to food production. Weed species such as *Cuscuta* spp. are especially noxious as they also directly extract valuable water and nutrients from the host plant, and in some cases can also be difficult to eradicate.

Finally, in "*A Review on the Botanical, Phytochemical and Pharmacological Characteristics of* Cuscuta *Spp.*," Khadijeh Ahmadi et al. presents a review of the botanical, phytochemical, and pharmacological characteristics for the holoparasite *Cuscuta* spp. in which he mainly states that the active compounds of *Cuscuta* spp. include flavonoids, lignans, quinic acid, and polysaccharides. Pharmacological studies and traditional uses of these plants have proved that they are effective antibacterial, antioxidant, antiosteoporotic, hepatoprotective, anti-inflammatory, antitumor, antipyretic, antihypertensive, analgesic, anti-hair fall, and antistereogenic agents.

> **Ana Maria Gonzalez** Instituto de Botánica del Nordeste (CONICET) - Universidad Nacional del Nordeste, Corrientes, Argentina

### **Héctor Arnaldo Sato**

Cátedra de Botánica general - Herbario JUA - Facultad de ciencias Agrarias UNJu, Jujuy, Argentina
