Orchids are an incredibly unique and fascinating group of plants. Many people can identify a Phalaenopsis (moth orchid) or Cattleya (the old corsage orchids), but the question often is asked, “What makes an orchid an orchid?” Orchids have some morphological (physical) traits that make them stand out from other plant families. In orchids, many of their floral parts come in groups of three. There are three sepals, which are the outer petals; these are what you see when you look at an unopened bud. There are also three petals, but in orchids one of the petals has been specialized into a labellum, or lip. This is usually the bottommost petal, and it helps to attract the pollinator to the reproductive organ. In orchids the reproductive organ, known as the column, combines both the male and female parts in one structure.
Masdevallia is one of my favorite types of orchids! They have triangular flowers (the petals are tiny, so you just see the three sepals.) They need cool temperatures to do well, and like a lot of humidity, but are otherwise quite easy to grow. (But they have a reputation as being hard to grow from people who've ignored their temperature and humidity requirements.)
The den-phal type are warm growing year round and do, just by happenstance, bear flowers similar in appearance to the genus Phalaenopsis. They can be distinguished by plant habit (most Dendrobium have pseudobulbs that resemble tall canes) and flower shape. Den-phals have a spur at the back of the lip; some are more pronounced, others less. They are also borne on very strong upright to barely arching stems. Interesting to note, den-phals can rebloom on old canes.
Most orchids are not heavy feeders. Many orchids bloom year after year with no fertilizer at all. During active growth, when new leaves are being produced, you may fertilize every other time you water at half the strength recommended on the fertilizer package. However, it's important to deliver water without fertilizer at least once a month to flush excess fertilizer salts from the bark mix and avoid fertilizer burn to the roots.