35.4
Desarrollo, estructura y función del fruto.
Los frutos se forman a partir de un ovario de flor madura. A medida que las semillas se desarrollan a partir de los óvulos contenidos en su interior,…
Las frutas son disfrutadas por muchos animales diferentes,
pero sirven una función importante para las plantas.
Una fruta es el ovario maduro de una flor.
Las frutas protegen las semillas y ayudan en la dispersión de semillas.
La fertilización causa cambios hormonales
que inician la transformación del ovario en fruto.
En ausencia de fertilización, Las flores en general
Se marchitan y no se convierten en fruta.
En las plantas con semillas, la estructura que da lugar
A las células reproductoras femeninas se llama
óvulo.
Los óvulos usualmente Se convierten en semillas
a medida que se desarrolla la pared del ovario en el pericarpio.
En una típico fruta carnosa, el pericarpio
consta de tres capas.
La capa exterior se llama epicarpio,
la porción media comestible se llama mesocarpio,
y la cubierta de la semilla dura interna es el endocarpo.
21 00: 00: 59,290 ---> 00: 01: 01,390 En algunas frutas como las vainas de guisantes, 22 00: 01: 01,390 ---> 00: 01: 04,080 El pericarpio está seco en la madurez. 23 00: 01: 04,080 ---> 00: 01: 06,370 En otras frutas, como los duraznos 24 00: 01: 06,370 ---> 00: 01: 09,370 El pericarpio se mantiene carnoso. 25 00: 01: 09,370 ---> 00: 01: 12,050 Las frutas pueden clasificarse de acuerdo a cómo se desarrollan 26 00: 01: 12,050 ---> 00: 01: 15,530 de los carpelos, las partes de las flores que contienen el óvulo. 27 00: 01: 15,530 ---> 00: 01: 18,810 Una fruta formada de un carpelo o carpelos fusionados 28 00: 01: 18,810 ---> 00: 01: 23,910 de un solo ovario de flores se llama una fruta simple. 29 00: 01: 23,910 ---> 00: 01: 26,590 Una fruta agregada, por el contrario, se origina 30 00: 01: 26,590 ---> 00: 01: 31,340 de múltiples carpelos separados de una sola flor. 31 00: 01: 31,340 ---> 00: 01: 33,270 Una fruta múltiple, por otra parte, 32 00: 01: 33,270 ---> 00: 01: 36,491 está formada por los muchos carpelos de las múltiples flores que 33 00: 01: 36,491 ---> 00: 01: 37,533 hacen una inflorescencia 34 00: 01: 37,533 ---> 00: 01: 40,140 35 00: 01: 40,140 ---> 00: 01: 42,530 En frutas accesorias, como las peras, 36 00: 01: 42,530 ---> 00: 01: 44,940 órganos distintos al ovario en gran parte 37 00: 01: 44,940 ---> 00: 01: 48,110 contribyen a la formación del fruto. 38 00: 01: 48,110 ---> 00: 01: 50,580 En general, una fruta madura permite que una planta 39 00: 01: 50,580 ---> 00: 01: 52,560 se propague al proteger sus semillas 40 00: 01: 52,560 ---> 00: 01: 56,500 de estresores ambientales y ayudando en su dispersión.
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Q1: What is a fruit and why do plants produce them?
A fruit is the mature ovary of a flower that develops after fertilization. Fruits serve two critical functions: they protect seeds from environmental stressors and aid in seed dispersal. This allows plants to propagate their species across wider geographic areas, increasing survival chances for their offspring.
Q2: How does fertilization trigger fruit development?
Fertilization initiates hormonal changes within the flower that transform the ovary into fruit. Without fertilization, flowers typically wither and fail to develop into fruit. Once fertilized, the ovule develops into a seed while the ovary wall undergoes complex changes to form the protective fruit structure.
Q3: What are the three layers of the pericarp in fleshy fruits?
The pericarp, or fruit wall, consists of three distinct layers. The epicarp is the outer protective layer, the mesocarp is the edible middle portion, and the endocarp is the innermost hard seed covering. In some fruits like peaches, the pericarp remains fleshy, while in others like pea pods, it dries at maturity.
Q4: How are fruits classified based on their developmental origin?
Fruits are categorized by the number of carpels and flowers involved in their formation. Simple fruits develop from one or fused carpels of a single flower. Aggregate fruits form from multiple separate carpels of one flower, while multiple fruits develop from many carpels of multiple flowers in an inflorescence.
Q5: What role do animals and environmental factors play in seed dispersal?
Fruits employ both biotic and abiotic dispersal mechanisms. Animals consume fruits and disperse undigested seeds through droppings, while wind and water carry seeds in specially adapted fruits. Some fruits, like pea pods, self-disperse by exploding. Water-dispersed seeds often have buoyant fruit, such as coconuts that float for months at sea.
Q6: What are accessory fruits and how do they differ from typical fruits?
Accessory fruits, such as pears, develop when organs other than the ovary largely contribute to fruit formation. Unlike simple, aggregate, and multiple fruits that arise primarily from carpel structures, accessory fruits incorporate additional floral tissues, creating a composite structure that still protects and disperses seeds.
Q7: What happens to seeds after fruit development is complete?
After fertilization and fruit development, seeds can remain dormant for months, years, or even decades until environmental conditions favor germination. This dormancy period allows seeds to survive unfavorable seasons and disperse to suitable locations. Understanding seed structure and early development helps explain how seeds eventually germinate and establish new plants.