Inocula

Inoculum (Plural: Inocula) [ Biology - Phytopathology - Tissue culture ]	Dictionary of botanic terminology index of names
Inoculation

PHYTOPATHOLOGY:

Any part or stage of a pathogen (e.g. spores, virus particles, mycelium ) capable to infect a host plant.
The amount of units of a microorganisms or parasite capable of initiating an infection

MICROBIOLOGY:

A medium containing organisms added to a sterilized substratum to start a culture or, in the case of viruses, viruses added to infect a culture of cells.
Also for biological material injected into a human to induce immunity (a vaccine): Bacteria or fungi injected into compost to start biological action.

HORTICULTURE:

The substance used to make an inoculation to a cultivation substratum.
The term is commonly applied to the application of a blend of microbial life forms, trace minerals, and nutrients to establish new populations in soils or composts, for example, Rhizobium bacteria are commonly applied as an inoculum to legume seeds.

Inoculation [ Phytopathology ]

The arrival or transfer of a pathogen onto a plant host.

To start a disease a pathogen must be introduced (inoculated) to the host plant. Most pathogens cannot move on their own, but must be carried to the host plant.
Pathogens are dispersed and carried to their host in different ways:

Water-borne pathogens: Carried by water. For example splashing rain carries spores of apple scab fungus from infected apple leaves to uninfected leaves.
Wind-born pathogens: Carried by wind. Wind blows fungal spores from plant to plant.
Soilborne pathogens: Refers to an organism that is more or less a permanent component of the soil flora.
Carried by animals (e.g. insect, bird etc.). The spotted cucumber beetle transmits bacterial wilt of cucumbers when feeding.
Carried by people: Smokers can transmit tobacco mosaic virus from a cigarette to tomato plants. Working in the garden when plants are wet is an other common way to spread disease.

Seeds or cuttings from infected plants will also transmit disease. Seeds are often coated with a fungicide to prevent the transmission of surface fungal diseases.

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Holdfast roots [ Botany ]
Dictionary of botanic terminology - index of names

Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.

Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans), develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994