Question: Crassula and Selinum, are different types of what?
Context: This page lists different types of expanders that are available for the process of palatal expansion in the field of orthodontics.  There can be many types of transverse dimension appliances.  These appliances can be used to achieve expansion in the maxillary arch, there is devices to mandibular expansion or lower expansion too.  In past many years, different types of appliances have been made.  These types are: 1) Tissue-borne 2) Tooth-borne 3) Slow Maxillary Expansion Type 4) Rapid Maxillary Expansion Type 5) Bone-Anchored Type Ingredient-flavor networks are networks describing the sharing of flavor compounds of culinary ingredients.  In the bipartite form, an ingredient-flavor network consist of two different types of nodes: the ingredients used in the recipes and the flavor compounds that contributes to the flavor of each ingredients.  The links connecting different types of nodes are undirected, represent certain compound occur in each ingredients.  The ingredient-flavor network can also be projected in the ingredient or compound space where nodes are ingredients or compounds, links represents the sharing of the same compounds to different ingredients or the coexistence in the same ingredient of different compounds. Disposing trash on Earth mainly comes in three ways: littering, incinerating, and storing in it the many landfills we have around the world.  With today’s landfills, there are very constructed contaminate structures.  These systems are designed to help keep solid waste from becoming too uncontained and uncontrolled from the environment and the impact it could have on the health of humans.  The purpose of having a liner system within a landfill is mainly to isolate everything within the landfill from the environment and protect it from contaminating the contents of the soil and especially the water within the ground.  These liners are engineered to create a physical barrier between the garbage within the landfill, the ground, and the environment, in order to separate the liquid contaminate (leachate) so that it can go to a treatment facility.  There are different types of these landfill sites for the different types of solid wastes which society creates and leaves behind.  There are certain levels of harmfulness in which the different types of trash have; therefore, there are different types of liner systems which are required for these different types of disposal sites.  The first type is single liner-systems.  These systems usually are put within landfills which mostly hold construction rubble.  These landfills are not meant to hold the disposal of harmful liquid wastes such as paint, tar, or any other type of liquid garbage that can easily seep through a single liner system.  The second type is double-liner systems.  These systems are usually found in municipal solid waste landfills as well all hazardous waste landfills.  The first part is constructed to collect the leachate while the second layer is engineered to be a leak-detection system to ensure that no contaminates leak into the ground and contaminate everything. In mathematics, topological degree theory is a generalization of the winding number of a curve in the complex plane.  It can be used to estimate the number of solutions of an equation, and is closely connected to fixed-point theory.  When one solution of an equation is easily found, degree theory can often be used to prove existence of a second, nontrivial, solution.  There are different types of degree for different types of maps: e.g. for maps between Banach spaces there is the Brouwer degree in R, the Leray-Schauder degree for compact mappings in normed spaces, the coincidence degree and various other types.  There is also a degree for continuous maps between manifolds. Crassula is a genus of succulent plants containing about 1480 accepted species, including the popular jade plant ("Crassula ovata").  They are native to many parts of the globe, but cultivated varieties originate almost exclusively from species from the Eastern Cape of South Africa. A mail bag or mailbag is a generic term for a type of bag used for collecting, carrying, categorizing, and classifying different types of postal material, depending on its priority, destination, and method of transport.  It is oftentimes used by a post office system in transporting these different grades of mail.  The "mailbag" is carried by some means of transporting like a mail carrier, animal ("e.g.", mule, horse), or a mobile post office.  Letters and printed material delivered by mail in the seventeen-hundreds were carried by horse in a saddle bag.  There are several different types of "mailbags" for different purposes ("e.g.", transporting mail to and from post offices, delivering mail to businesses and homes.  These different styles of mailbags depend on its size and purpose.  It can range from "a large bag used for transporting mail on a truck, plane, etc." to a simple "postbag" used by a mail carrier to deliver mail. Multi-amp guitar rigs use two or more amplifiers to create a unique tone that could not be achieved with the use of only one amplifier.  Guitar players such as James Valentine (Maroon 5) and John Mayer use multiple amplifiers simultaneously to achieve their tones.  Session guitar players such as Brent Mason often bring four or more amplifiers to recording sessions.  There are many different types of guitar amplifiers that have drastically different sounds.  There are three classic guitar amplifier circuits that most amplifiers are based on that all use different power amplifier tubes: The EL84 powered class A circuits which comes from the Vox AC30 and AC15 amplifiers, The 6L6 and 6V6 powered class AB circuits which come from Fender amplifiers, and the EL34 powered class AB circuits which come from Marshall amplifiers.  The sonic characteristics of these different amplifier configurations are extremely different and for a lot of guitar players it is important to have the tonal palette of all three.  This is especially true for studio guitarists and is why a lot of high-end recording studios have multiple different types of guitar amplifiers in house.  It is a common practice to use a 6L6 or 6V6 powered amplifier for a clear, clean tone in conjunction with an EL34 or EL84 powered amplifier for a more distorted tone.  It is then a matter of blending the two amps' signals in order to achieve the desired amount of distortion. Comparative criminal justice is a subfield of the study of Criminal Justice that compares justice systems worldwide.  Such study can take a descriptive, historical, or political approach.  It studies the similarities and differences in structure, goals, punishment and emphasis on rights as well as the history and political stature of different systems.It is common to broadly categorize the functions of a criminal justice system into policing, adjudication (i.e.: courts), and corrections, although other categorization schemes exist.  Comparativists study the four different types of societies, their methods of enforcement and their different types of punishment such as capital punishment, and imprisonment.  Within these societies they study different types of legal tradition and analyze the issues they solve and create.  They use their information in order to learn effective ways of enforcing laws, and to identify and solve problems that may arise within a system due to its methods. Selinum is a genus of flowering plant in the family Apiaceae. Bohnanza is a German-style card game of trading and politics, designed by Uwe Rosenberg and released in 1997 by Amigo Spiele in German and by Rio Grande Games in English.  It is played with a deck of cards with comical illustrations of eleven different types of beans (of varying scarcities), which the players are trying to plant and sell in order to raise money.  The principal restriction is that players may only be farming two or three types of bean at once, but they obtain beans of all different types randomly from the deck, and so must engage in trading with the other players to be successful.  The original game is for three to five players and takes about one hour to play, but the Rio Grande edition adds alternative rules to allow games for two or seven players.
Answer: plants